***The Hotness™️ Build Thread!***

djlythium

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Hey, everyone! I figured it was my turn to contribute. 😄 Now using this thread to detail The Hotness™️‘s build. I plan on showing more of the nuances of issues that arise with common installs, trying to answer questions i wish were answered before starting these installs. Plus, I’ll use this space for pics of Hottie. Enjoy! Questions/comments welcomed!

***TEIN Flex Z + 2020CTR & Acuity Stage 2 + Mishimoto INSTALL!
Finally was able to check off some of the installs on my Mod List, and this round includes:

- TEIN Flex Z (w/ ADS cancellers): chose this kit because it's a fantastic combo of quality, cost, and including necessary parts (like the ADS cancellers).
- 2020 CTR Shifter & Acuity Stage 2 kit: seems like the perfect set-up for a street car (of course, 'perfect' being subjective', though it seems like most are saying the full shifter upgrade can be a bit too tight and harsh), and you kinda can't really beat the total cost per upgrade potential.
- Mishimoto SRI: definitely NOT looking for HP or TQ gains (if I was, I'd just flash the comp, and be done with it), but rather better sssSSSSSSS PSSHHHHHhhh sounds, plus it's CARB-legal!

While I'm happy to answer any questions folks might have about parts & install, I won't be going into any specific write-ups here because there are a bunch on CIVICX. I WILL, however, be filling in the gaps in knowledge that I found around the interwebs, trying to answer unknowns for which I could find no solutions/responses.

Lessons:

TEIN Flex Z Install

FRONT SET-UP

- My biggest concern was damaging my axles. Y'all, I lost sleep going over, time and again, the install procedure I synthesized from a variety of videos, plus other peoples' stories around here. Main concerns: pulling out the axles from the transaxle and/or tearing the boot on the LCA. I couldn't find any pics of the sharp metal associated with ripping the boot, so, I took a pic, along with my temporary protective solution: a five-layer 6" strip of duct tape. 😄 In the pic, you can see the t-bar sticking up on the LCA just underneath the axle, as if Honda was like 'FU anyone who's going to lower your car without using our complicated instructions!'. The duct tape created a leathery barrier that would stick in place to cover that whole t-bar piece, and that I could reuse on the other side of the car.

IMG_0672.jpeg

IMG_0673.jpeg

IMG_0675.jpeg


- Regarding pulling out the axles: after separating the hub from the LCA (which looks MUCH easier in videos than it actually is in real life when trying to be super-careful), I basically cradled the hub in my lap while allowing only enough play to tip the top of the hub inward and forward to allow the bottom of the strut to pop out (I had only loosened the nuts on the strut tower to allow the strut to mingle a little bit, facilitating maneuverability). Once the strut was free from the hub, I immediately placed the hub back into the LCA so it wouldn't dangle, securing it with a hand-tightened nut. 😅 Once the hub was secured, I tried rotating the rotor by hand to ensure it was still engaged in the transaxle, and I could see it rotating the other front rotor (I put the car in gear before starting all of the as a double-check).

- Now, some said the driver's side was the most difficult, but I found the passenger side to be hardest. The hub just seemed to have a tad less play than the other side, so, I couldn't drop the hub low enough, at least, not without other assistance. I ended up using spring compressors for this side, and had a friend step on the hub just enough to free the strut. Afterward, again, I immediately went about securing the hub back into the LCA, and checking the axle for damage. On this side, the axle did barely disconnect from the intermediary shaft, but it slipped right back in with ease. I did a series of rotations of the rotor to ensure I could still feel the transaxle, the other side was also rotating (denoting the connection through the LSD), and I also checked the axle for any weird wobbling (basically, just looking for any sign that something could be possibly damaged). Luckily, everything seemed just fine! 😅 As always, ensure the nipple on the rear of the strut fits into the gap on the hub's upper mount.
IMG_0676.jpeg


- I secured the EDFC cancellers with black zip-ties, and while I tried a variety of different options, I found this in the pics to be the best compromise that did not put too much stress on the wiring.
IMG_0677.jpeg


REAR SET-UP
- Inconveniently, on the coupe, there is no agreed-upon single rear jack point analogous to the front. 🤦🏼‍♂️ Some have said they use either of the two flat brackets on either side of the exhaust, located inward-center of the rear tires, but others have said these brackets bend over time. Even Honda shows no single point for the Si Coupe (TMK! I looked everywhere, but I'm open to being more informed on this). So, I first disconnected the rear sway bar from both sides while the car was on the ground, then did one side at a time. Because I bought the Flex Z to stance the car, I knew I also needed to adjust the rear shocks' lower bracket and locking ring along with the springs' HAS (Height Adjustment System, TEIN's term for the threaded spring perch). However, there was no info in TEIN's little (rather incomplete) manual, so, I contacted them directly, to which they replied "Yes, when adjusting the rear spring seat position on the HAS, be sure to also adjust the shock absorber length. For 5mm of adjustment of the spring seat, adjust the shock absorber 8mm. Once you've set your desired ride height, please remember to torque down the seat locks/bracket locks to the specified torque." Emphasis added. Ah ha! After doing some measurements as described in their book, I needed to shorten the shock body by 25mm, which ended to basically taking up all of the adjustment room in the lower mounting cup. I basically have the rear shocks as short as they will go (remember this is uncompressed. I'm just adjusting the lower mounting point).

- Mounting the HAS (the threaded spring perch): the HAS fits over the nub on the chassis (not the LCA), but the tolerance isn't too tight, the solution to which is provided by TEIN in the form of some double-sided tape. This tape is a PITA to work with, and after trying multiple methods, I found the best to be to wrap the upper-edges of the nub with a 1' strip of the tape, stretching the tape a bit as you go. This seemed to act as an 'adapter' of sorts to mount and hold the HAS.
IMG_0679.jpeg

IMG_0678.jpeg


- Installing the spring into the LCA: I found it easiest to first pop the lower rubber mount into the LCA, ensuring the little nipples pop into their respective holes, then twist the spring into the rubber mount until it stops.

OVERALL

- Perfect ride! Silent, solid, but totally streetable (and I have lower back issues!) No error codes, everything working swimmingly! Love it!
Advertisement

 
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djlythium

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Mishimoto Intake

- While removing the battery isn't necessary, I was going to later install the Acuity bushings, so, I just removed the intake and airbox + the battery while I was up top. After disconnecting the flexible tube from the hard black plastic turbo inlet pipe, and removing the two bolts that secure the airbox to the frame, I found I had to pull upward with some considerable force to pop the upper airbox free from the lower resonator. I was concerned I might break something, but everything turned out fine.
IMG_0669.jpeg


- Since the Mishi intake is CARB-legal, I knew I wasn't ever going to need the stock airbox & resonator again, so, I wanted to remove the dead-weight resonator. I commend anyone who had the patience to try to unbolt the two bolts underneath the resonator while working from the top! 😧 Wow! I removed only the lower silver splash guard, and worked at those two bolts from underneath. That front-most bolt (the smaller one in the rightmost circle in the pic) was a PITA! Ended up getting it, though. Be patient!
IMG_0670.jpeg


- Otherwise, the install was easy, and the sounds are orgasmic! 😋 JUST what I was looking for! sssssSSSSSSSS PSSSSSHHHHHHhhhhh, every time. Shout out to @Mishimoto for a high-quality product! Love it!
IMG_0681.jpeg


Acuity Parts + CTR Shifter

- The biggest PITA with this install is getting the shifter cable retainer clips off, but, otherwise, follow Acuity's instructions, and you'll be fine. The interior disassemble was pretty easy, again thanks for Acuity's thorough instructions, and if you don't have the interior removal tools, GET THEM! The cost/benefit is totally in your favor. TIPS: 1) go slow, try to pry underneath the parts that are coming off so you don't damage exterior-facing surfaces. 2) Small tools are super-helpful for undoing clips (e.g., a hook tool, small pick, or small screwdriver), and the clip ‘fingers’ will always be in a position that is the hardest to get to with your fingers, especially those on the shifter assembly itself. 3) Speaking of which, I unbolted the shifter assembly so I could manipulate into a position that actually allowed me to get my fingers/a toll on the inside to udo the wiring clips. Again, if you follow their install guide, you’ll be fine. So, shout out to @ACUITY for high-quality products + thorough install instructions!
IMG_0682.jpeg


Otherwise, questions/comments welcomed! Once I get the rims, I’ll snap a full body pic. 😄😎

Other pics!
IMG_0664.jpeg

IMG_0651.jpeg

IMG_0025.jpeg
 
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djlythium

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What is the
Mishimoto Intake

- While removing the battery isn't necessary, I was going to later install the Acuity bushings, so, I just removed the intake and airbox + the battery while I was up top. After disconnecting the flexible tube from the hard black plastic turbo inlet pipe, and removing the two bolts that secure the airbox to the frame, I found I had to pull upward with some considerable force to pop the upper airbox free from the lower resonator. I was concerned I might break something, but everything turned out fine.
IMG_0669.jpeg


- Since the Mishi intake is CARB-legal, I knew I wasn't ever going to need the stock airbox & resonator again, so, I wanted to remove the dead-weight resonator. I commend anyone who had the patience to try to unbolt the two bolts underneath the resonator while working from the top! 😧 Wow! I removed only the lower silver splash guard, and worked at those two bolts from underneath. That front-most bolt (the smaller one in the rightmost circle in the pic) was a PITA! Ended up getting it, though. Be patient!
IMG_0670.jpeg


- Otherwise, the install was easy, and the sounds are orgasmic! 😋 JUST what I was looking for! sssssSSSSSSSS PSSSSSHHHHHHhhhhh, every time. Shout out to @Mishimoto for a high-quality product! Love it!
IMG_0681.jpeg


Acuity Parts + CTR Shifter

- The biggest PITA with this install is getting the shifter cable retainer clips off, but, otherwise, follow Acuity's instructions, and you'll be fine. The interior disassemble was pretty easy, again thanks for Acuity's thorough instructions, and if you don't have the interior removal tools, GET THEM! The cost/benefit is totally in your favor. TIPS: 1) go slow, try to pry underneath the parts that are coming off so you don't damage exterior-facing surfaces. 2) Small tools are super-helpful for undoing clips (e.g., a hook tool, small pick, or small screwdriver), and the clip ‘fingers’ will always be in a position that is the hardest to get to with your fingers, especially those on the shifter assembly itself. 3) Speaking of which, I unbolted the shifter assembly so I could manipulate into a position that actually allowed me to get my fingers/a toll on the inside to udo the wiring clips. Again, if you follow their install guide, you’ll be fine. So, shout out to @ACUITY for high-quality products + thorough install instructions!
IMG_0682.jpeg


Otherwise, questions/comments welcomed! Once I get the rims, I’ll snap a full body pic. 😄😎

Other pics!
IMG_0664.jpeg

IMG_0651.jpeg

IMG_0025.jpeg
Mishimoto Intake

- While removing the battery isn't necessary, I was going to later install the Acuity bushings, so, I just removed the intake and airbox + the battery while I was up top. After disconnecting the flexible tube from the hard black plastic turbo inlet pipe, and removing the two bolts that secure the airbox to the frame, I found I had to pull upward with some considerable force to pop the upper airbox free from the lower resonator. I was concerned I might break something, but everything turned out fine.
IMG_0669.jpeg


- Since the Mishi intake is CARB-legal, I knew I wasn't ever going to need the stock airbox & resonator again, so, I wanted to remove the dead-weight resonator. I commend anyone who had the patience to try to unbolt the two bolts underneath the resonator while working from the top! 😧 Wow! I removed only the lower silver splash guard, and worked at those two bolts from underneath. That front-most bolt (the smaller one in the rightmost circle in the pic) was a PITA! Ended up getting it, though. Be patient!
IMG_0670.jpeg


- Otherwise, the install was easy, and the sounds are orgasmic! 😋 JUST what I was looking for! sssssSSSSSSSS PSSSSSHHHHHHhhhhh, every time. Shout out to @Mishimoto for a high-quality product! Love it!
IMG_0681.jpeg


Acuity Parts + CTR Shifter

- The biggest PITA with this install is getting the shifter cable retainer clips off, but, otherwise, follow Acuity's instructions, and you'll be fine. The interior disassemble was pretty easy, again thanks for Acuity's thorough instructions, and if you don't have the interior removal tools, GET THEM! The cost/benefit is totally in your favor. TIPS: 1) go slow, try to pry underneath the parts that are coming off so you don't damage exterior-facing surfaces. 2) Small tools are super-helpful for undoing clips (e.g., a hook tool, small pick, or small screwdriver), and the clip ‘fingers’ will always be in a position that is the hardest to get to with your fingers, especially those on the shifter assembly itself. 3) Speaking of which, I unbolted the shifter assembly so I could manipulate into a position that actually allowed me to get my fingers/a toll on the inside to udo the wiring clips. Again, if you follow their install guide, you’ll be fine. So, shout out to @ACUITY for high-quality products + thorough install instructions!
IMG_0682.jpeg


Otherwise, questions/comments welcomed! Once I get the rims, I’ll snap a full body pic. 😄😎

Other pics!
IMG_0664.jpeg

IMG_0651.jpeg

IMG_0025.jpeg

Hey, everyone! I figured it was my turn to contribute. 😄



Finally was able to check off some of the installs on my Mod List, and this round includes:

- TEIN Flex Z (w/ ADS cancellers): chose this kit because it's a fantastic combo of quality, cost, and including necessary parts (like the ADS cancellers).
- 2020 CTR Shifter & Acuity Stage 2 kit: seems like the perfect set-up for a street car (of course, 'perfect' being subjective', though it seems like most are saying the full shifter upgrade can be a bit too tight and harsh), and you kinda can't really beat the total cost per upgrade potential.
- Mishimoto SRI: definitely NOT looking for HP or TQ gains (if I was, I'd just flash the comp, and be done with it), but rather better sssSSSSSSS PSSHHHHHhhh sounds, plus it's CARB-legal!

While I'm happy to answer any questions folks might have about parts & install, I won't be going into any specific write-ups here because there are a bunch on CIVICX. I WILL, however, be filling in the gaps in knowledge that I found around the interwebs, trying to answer unknowns for which I could find no solutions/responses.

Lessons:

TEIN Flex Z Install

FRONT SET-UP

- My biggest concern was damaging my axles. Y'all, I lost sleep going over, time and again, the install procedure I synthesized from a variety of videos, plus other peoples' stories around here. Main concerns: pulling out the axles from the transaxle and/or tearing the boot on the LCA. I couldn't find any pics of the sharp metal associated with ripping the boot, so, I took a pic, along with my temporary protective solution: a five-layer 6" strip of duct tape. 😄 In the pic, you can see the t-bar sticking up on the LCA just underneath the axle, as if Honda was like 'FU anyone who's going to lower your car without using our complicated instructions!'. The duct tape created a leathery barrier that would stick in place to cover that whole t-bar piece, and that I could reuse on the other side of the car.

IMG_0672.jpeg

IMG_0673.jpeg

IMG_0675.jpeg


- Regarding pulling out the axles: after separating the hub from the LCA (which looks MUCH easier in videos than it actually is in real life when trying to be super-careful), I basically cradled the hub in my lap while allowing only enough play to tip the top of the hub inward and forward to allow the bottom of the strut to pop out (I had only loosened the nuts on the strut tower to allow the strut to mingle a little bit, facilitating maneuverability). Once the strut was free from the hub, I immediately placed the hub back into the LCA so it wouldn't dangle, securing it with a hand-tightened nut. 😅 Once the hub was secured, I tried rotating the rotor by hand to ensure it was still engaged in the transaxle, and I could see it rotating the other front rotor (I put the car in gear before starting all of the as a double-check).

- Now, some said the driver's side was the most difficult, but I found the passenger side to be hardest. The hub just seemed to have a tad less play than the other side, so, I couldn't drop the hub low enough, at least, not without other assistance. I ended up using spring compressors for this side, and had a friend step on the hub just enough to free the strut. Afterward, again, I immediately went about securing the hub back into the LCA, and checking the axle for damage. On this side, the axle did barely disconnect from the intermediary shaft, but it slipped right back in with ease. I did a series of rotations of the rotor to ensure I could still feel the transaxle, the other side was also rotating (denoting the connection through the LSD), and I also checked the axle for any weird wobbling (basically, just looking for any sign that something could be possibly damaged). Luckily, everything seemed just fine! 😅 As always, ensure the nipple on the rear of the strut fits into the gap on the hub's upper mount.
IMG_0676.jpeg


- I secured the EDFC cancellers with black zip-ties, and while I tried a variety of different options, I found this in the pics to be the best compromise that did not put too much stress on the wiring.
IMG_0677.jpeg


REAR SET-UP
- Inconveniently, on the coupe, there is no agreed-upon single rear jack point analogous to the front. 🤦🏼‍♂️ Some have said they use either of the two flat brackets on either side of the exhaust, located inward-center of the rear tires, but others have said these brackets bend over time. Even Honda shows no single point for the Si Coupe (TMK! I looked everywhere, but I'm open to being more informed on this). So, I first disconnected the rear sway bar from both sides while the car was on the ground, then did one side at a time. Because I bought the Flex Z to stance the car, I knew I also needed to adjust the rear shocks' lower bracket and locking ring along with the springs' HAS (Height Adjustment System, TEIN's term for the threaded spring perch). However, there was no info in TEIN's little (rather incomplete) manual, so, I contacted them directly, to which they replied "Yes, when adjusting the rear spring seat position on the HAS, be sure to also adjust the shock absorber length. For 5mm of adjustment of the spring seat, adjust the shock absorber 8mm. Once you've set your desired ride height, please remember to torque down the seat locks/bracket locks to the specified torque." Emphasis added. Ah ha! After doing some measurements as described in their book, I needed to shorten the shock body by 25mm, which ended to basically taking up all of the adjustment room in the lower mounting cup. I basically have the rear shocks as short as they will go (remember this is uncompressed. I'm just adjusting the lower mounting point).

- Mounting the HAS (the threaded spring perch): the HAS fits over the nub on the chassis (not the LCA), but the tolerance isn't too tight, the solution to which is provided by TEIN in the form of some double-sided tape. This tape is a PITA to work with, and after trying multiple methods, I found the best to be to wrap the upper-edges of the nub with a 1' strip of the tape, stretching the tape a bit as you go. This seemed to act as an 'adapter' of sorts to mount and hold the HAS.
IMG_0679.jpeg

IMG_0678.jpeg


- Installing the spring into the LCA: I found it easiest to first pop the lower rubber mount into the LCA, ensuring the little nipples pop into their respective holes, then twist the spring into the rubber mount until it stops.

OVERALL

- Perfect ride! Silent, solid, but totally streetable (and I have lower back issues!) No error codes, everything working swimmingly! Love it!
How many inches are you lowered for the front and back? if you don’t mind me asking? And how did you set your preload?
 
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djlythium

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What is the

How many inches are you lowered for the front and back? if you don’t mind me asking? And how did you set your preload?
Hello!

Right now, the zenith of the wheel well arch is 25 1/4” from the ground, across all four corners, which means the rear as lowered a bit more than the front to level the car out. This translates into about a 2 1/4” drop in the rear, and 2“ in the front. That said, I’m not at my final height yet, as I want to go a bit lower.

Preload was set from the factory by TEIN. I didn’t touch it, just ensured the rings were tight.

EDIT: 1.5 rear, 1.25 front. Once I get my rims, I plan on going lower.
 
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For us in Cali, I'm surprised the Mishimoto intake doesn't get more attention. It's easy to install, legal and doesn't require the bottom box to be removed, so there is no need to get under the car to install (and clean the filter). I love the sound of mine and when it comes to servicing the filter, I open the hood and remove four hex screws.

However, from what I've seen and heard on Youtube, the hiss isn't nearly as noticeable as the PRI true CAI, but that's a trade off I'm more than happy to have made with the Mishi intake.

Awesome write @djlythium by the way.
 
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For us in Cali, I'm surprised the Mishimoto intake doesn't get more attention. It's easy to install, legal and doesn't require the bottom box to be removed, so there is no need to get under the car to install (and clean the filter). I love the sound of mine and when it comes to servicing the filter, I open the hood and remove four hex screws.

However, from what I've seen and heard on Youtube, the hiss isn't nearly as noticeable as the PRI true CAI, but that's a trade off I'm more than happy to have made with the Mishi intake.

Awesome write @djlythium by the way.
Yeah, I totally agree with your points. I haven’t heard the PRL in-person, so, I cannot compare, but given how loud the Mishimoto is + being CARB-legal + being high-quality and easy to install, it’s the perfect choice, IMO.

Thanks!
 
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Been playing around again 😄.

1606290648288.jpeg


My dream Riza: my rims coming this week + shaved handles + a translucent smoked duckbill spoiler. 😍

Shoutout to @PdxJose for the base image!
 
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civicsicoupe20

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Hey man what acuity parts did you add for the 2020 ctr shifter?
Acuity Shifter Rocker upgrade
Performance Shifter Centering spring
Shiter base bushing
Shifter Cable bushing upgrade

is that all you need?

I went to @ACUITY website and they don't offer the whole stage 2 kit I guess you need to buy them separately now.

Thanks
 
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Hey man what acuity parts did you add for the 2020 ctr shifter?
Acuity Shifter Rocker upgrade
Performance Shifter Centering spring
Shiter base bushing
Shifter Cable bushing upgrade

is that all you need?

I went to @ACUITY website and they don't offer the whole stage 2 kit I guess you need to buy them separately now.

Thanks
SRY, just saw this!

Acuity Parts: https://acuityinstruments.com/colle..._10th_gen_civic_stage_2_shift_kit_for_the_fk8

OEM 2020 CTR Shifter: https://www.hondapartsnow.com/genuine/honda~0~54100-tgh-g01.html

I also recommend getting Acuity's interior panel tools. They're super-helpful, and not very expensive at all.
 
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Okay, UPDATES! Finally got my rims in!

TSW Chronos, 18x8.5 +30. Tires are 235/40/18 Federal 595s (had these on a prior vehicle, and loved them because they never tramlined, and I like the tread pattern.)
IMG_0050.jpeg

IMG_0698.jpeg


Now, I know I was rolling the dice with this set-up with the TEINs at full drop, and, sure enough, I didn't even make it out of the driveway. 😄 The front fenders were, literally, on the tire. So, I've raised up both the front an rear to be about a 1.5" drop in the front, and a 1.75" drop in the rear to level out the car. Plus, I added some negative camber to the front (about three marks inward using the indicators on the hat). Now, there's only a little rubbing on the front tires over bumps, but this is due to a small part of the front fenders' inner lining next to the sidemarker. This model year eliminated the fender tab in that location, so, I'll keep an eye on it, but I'll have to consider a fix here soon.

In these pics, the fender is about 1/4" from the tire, and this was before raising it up:
IMG_0702.jpeg

IMG_0703.jpeg


Here's how she sits now:
IMG_0700.jpeg

IMG_0704.jpeg

Flush AF!

I'll post better pics once she's all washed up! 😎
 
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Okay, finally! Pic dump!

Stats as she sits now:
TSW Chronos 18x8.5 wrapped in 235/40/18 Federal 595s

TEIN Flex Zs lowered to a 1.5” drop in the front, 1.75” drop in the rear.

Slight rubbing in the front on the inner fender liner near the inside of the side marker, only on bigger bumps.

Questions/comments welcomed!

EB988860-522A-4060-B78F-3F7D0FEA1BEC.jpeg


80852F42-86CA-4CB2-932A-8CC511091804.jpeg


89CD9CB5-8560-45B7-B20D-91A49DACD863.jpeg


14BC60F7-1682-4FC9-BC10-113BF6112AD3.jpeg


2D577E5F-CDAE-4DAB-970B-A9B8FE4A914A.jpeg


88D9A4A9-1095-47B9-97D3-3CA22532E36B.jpeg


ED223B48-39AE-44BE-ABD3-8A3A2F776F70.jpeg


99170FE8-B0D9-49EB-B9F5-D608779581F4.jpeg
 
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Tuning Update: Given the stance of the coilovers, I had some rubbing in the front on any bump other than mild. So, I set the front coils to max-negative camber this morning, and that seemed to eliminate most rubbing except for really large bumps.

Just a friendly PSA! ✌🏼😎
 
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djlythium

djlythium

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Location
California
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2019 CBP Si Coupe
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Whew! OMGosh, what a week! So, my next big batch-install is the Greddy DD-R exhaust, an AeroFlow Dynamics full aero kit, purple Muteki SR48 lug nuts 😄,+ some vinyl work that mostly didn’t actually work out.😒 You‘ll see why below.

The Hotness™️ gets a weight reduction!

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😄 Also, Greddy DD-R installed!

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In my personal opinion, this has a perfect exhaust sound. Not raspy at. All., nice and deep, but not overpoweringly loud, but certainly louder than stock, zero drone except a very tiny bit when on throttle passing 2K rpm, but all other cruising is totally fine. In fact, on the freeway last night, it was so quiet at normal cruising speeds that I thought i might’ve messed up the install in some way. 😅 But, nope, just very well engineered. @ WOT, the exhaust is throaty, but refined, and has zero annoying high-pitched rasp; it’s sounds amazing. Also, noticed my throttle response is just a tad snappier, which is nice side-effect. Off-throttle, between shifts, there’s just a tiny bit of gurgle, which is pretty neat.

Overall fitment is excellent. If I had any concerns, they’d be 1) Greddy supplies all install hardware, which is great. However, the 3 bolts on the downpipe, to which the resonated-portion of the exhaust attaches, seem like they’re part of the downpipe itself. Greddy provides three bolts + nuts to go there, presumably, but it didnt seem like the OEM downpipe bolts could be removed (and no install instructions provided). I ended up reusing the factory nuts. Maybe my 2019 had a small change from prior years? 🤷🏼‍♂️ I checked all connection points for leaks after install, and everything seemed fine and solid. And 2) when tightening up the midpipe to exhaust connection section, I noticed the midpipe was touching one of the two metal brackets attached to the body at the section. I thought it’d be a rubbing issue, but once everything was all tightened up, the exhaust piping all self-aligned, and there was no more rubbing issue. The long test drive afterward confirmed all was well. So, overall, during the install, always checking things as I went, I thought there’d be some issues, but everything turned out fine. 😄

I will recommend, though, that due to the tight clearances of the 3” tubing, you’ll need a 14mm socket that is relatively thin-walled (I used a 3/8” drive socket on the impact wrench), and I highly recommend a universal joint to help reach the nuts correctly.

Took me 3 hrs total, the longest portion of which was trying to remove the hangers from the body. 😧😖 Those were a b****! Lube, lube, lube!

UPDATE: 2 months later, now that the metal is ’broken in’, and the engine has adjusted to the exhaust, whatever little drone was present @ 2K RPM is the same (which is good), but the overall sound is throaty but smooooooth as ever, and I have new pops and gurgles when shifting. 🤤 Such a perfect sound, IMO!


Next, Hottie gets a new skirt!

The Aeroflow Dynamics Full Kit elements I chose are:
The 2016-2020 Honda Civic Si Rear Diffuser V1 for the coupe
The 2017-2020 Honda Civic Splitter ([Hatchback, Si Coupe, Si Sedan]) V2
2016-2020 Honda Civic Side Skirt Extension V4 for the coupe

☝🏼 Installed in that order.

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I wavered between this kit or the Downforce Solutions, but I ended up liking this one just a tad more. That said, I wondered if the diffuser would be compatible with the Greddy DD-R exhaust. It's not*. See below!

PROS: the quality of the parts is wonderful! The gloss black powdercoat looks great.
CONS:
• ZERO installation instructions! No wonder they say 'professional installation recommended.' 🙄 Their three online install videos are for cars that aren't the CivicX, so... YT it is! I used a combination of videos to create a personalized install regimen.
• The fitment was so-so. The side-strakes of the diffuser don't match up to the underside of the sides of the bumper, and neither did the front splitter fit perfectly on the ends of the underside of the bumper (pics below). I definitely had to use some 'creative freedoms' during the install, which I'll detail next!

Okay, let's get to it! Also, apologies ahead of time for some for the pics looking like they've been rotated 90 degrees. Civicx(dot)com automatically rotated some of my pics. 🤷🏼‍♂️ You get the idea, though.

DIFFUSER
Center section:
In this pic, the top bolt/spacer set is about 1/2" for the front-most portion of the diffuser. The bottom bolt/spacer set if about 3/8" for the rear-most portion of the diffuser. The washers/spacers should be in this order. There are pairs for both sides.
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Here is a top-down of the center section. The smaller bolts on the bottom of the pic are for the side strakes. They show the ordering of the washers.
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Here is the front edge of the underside of the rear bumper, right next to the Greddy muffler. The hole indicates a pop-clip removed because that's where the 1/2" bolt/spacer combo will go, and, luckily, attaches to a stabilizer tracker that's already part of the car! I was kinda wondering if the diffuser would cause sag over time if the rear lower part of the bumper was not attached to anything, but, nope, should all good!
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This next pic shows that bracket I was talking about, and I mocked up how the bolt is supposed to go. The spacer goes between the diffuser and the bumper plastic.
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This next pic shows the center section attached with the front bolts. I'm pressing the rearmost part upward to show it aligning with the bumper plastic.
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Remember that * from the comment above? This is it: the diffuser 'doesn't' work with the Greddy DD-R is it's supposed to not touch. In this pic, I highlighted where the diffuser barely touches the exhaust. Later on, I used washers to more space (about 1/2") on top of the front spacers installed in the prior step, but it only made a small difference. I think 1" spacers all around would be best if I want no rubbing at all. I talk more about the potential for rattling & thermal damage down below.
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Side Strakes:
Okay, on to the sides! I used a combination of painters tape + a jack (not pictured. Also, I used some of the packaging filler padding as a barrier between the jack contact pad and the underside of the strake. Wanted to keep the finish nice! You'll see in other pics how I creatively used the packaging padding to hold pieces in place during mock up.) so hold the strake in position while I maneuvered it to right where I wanted it (using Aeroflow's product pics as a guide).
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Here's the underside of the edge of the rear bumper right behind the rear tire. The bolt got cinched down, but I wanted to show how the fitment was a bit off. See that curved portion of the strake? It's sitting on a small lip of plastic. I could've pushed it out more, toward the outside of the car, but I wanted the strake flush with the bumper. PLUS, as you'll see in the next pic, the hole I had to drill for this bolt at this location was right on an angle on the inside of the bumper. Any more outward, and the mounting would be impossible; any more inward, and the strake wouldn't be flush. Not sure how AD screwed this up (no pun intended), and with no instructions from them, I'm still at a loss. 🤷🏼‍♂️ Seems like a design flaw.
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...and here shows the nut for that front mounting bolt for the strake. See how it's on an angle? It looks loose, but it's actually cinched down was an impact wrench! It's a solid fitment (I wouldn't drive it if it wasn't), but I think I might order some 45-degree spacers just because I like it to be perfectly perfect. 😄
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Okay, on to the rear mounting point for the strake. So, straight-forward, drill a hole, right? Wrongo! In fact, that becomes a trend throughout the build. Anywho, this next pic shows the rearmost mounting bolt poking up right next to a small plastic mount on the inside of the bumper, a mounting point for an inner shroud. I could've removed it, but I wanted to keep most OEM parts, if I could. Getting the washer and nut onto this bolt was a B****!
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However, after all was done, measured, adjusted, and totally tightened down, the result is amazing! 😍 Take your time, and measure, measure, measure! In this pic, you can see how the strake is flush with the side of the bumper, and the angular cut of the strake flows into the rearmost upper edge of the diffuser. I love that flow-line!
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Splitter
Now, onto the front! Knowing that the splitter and the sideskirts watched with the little winglets, I wanted the sideskirts to follow the form-line of the splitter, which means I needed to mount the splitter first.

Splitter and sideskirts!
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Here is The Hotness with no front bumper! 😧 When I got the car, I never thought I would be removing the front bumper, but here we are. 😄 There are a variety of videos around detailing the removal of the front bumper, and I was a nervous wreck doing it! TAPE THE EDGES OF HEADLIGHTS, THE BUMPER, AND THE FENDER! For the love of the Car Gods, do it. You can see the tape I used in the pic. I'm confident I saved Hottie from a BUNCH of scratches due to the tape. 😰 While it was off, I took a moment to gently vacuum out any bugs that were stuck in the intercooler and/or around little pockets. I also tried carefully straightening some of the fins, but I didn't have the right tools. 🤷🏼‍♂️
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This next pic shows the clips of the bumper support right underneath the headlight, a pic I WISH I had so I knew where to place the trim tool when gently prying the bumper off. Still, I think I snapped one clip off on this side (third bump from the left), but here's rub: If I snap something, I always try to find the part snapped off. However, I could NOT find the clip! It vanished into thin air! I even removed the headlight unit, and shook it around in case the plastic piece got jammed somewhere, but there are only so many places it could go. Y'all, I looked everywhere, and couldn't find it. 🤷🏼‍♂️ I almost think it came like this from Honda, but I also highly doubt that. As this part is now discontinued (I checked!), 🤷🏼‍♂️. Battle scar, I guess.
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Okay, this is where the fun begins! You see how the bumper is upside-down? That's not an image error. And remember when I said I used the packaging padding in creative ways during mock-up? Here's one! This was the easiest way I could devise to mock-up the splitter into the underside of the front bumper so I knew where to drill holes. What you're looking at is the padding rolled up into varying thicknesses, and taped together to create a padding columns. The bumper is resting on three units, with one unit each under the eyebrow winglets (didn't want to stress those), and the bumper assembly itself is resting against a chair.
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Here is the splitter resting on the underside of the bumper. See the inner rearmost edges of the splitter resting on the rubber airdam (denoted with pink arrows)? That's no bueno. In this pic, the splitter's rearmost edges are flush with the rear edges of the front bumper (as Aeroflow's pics show), and with no instructions yet again 🙄 as to if this is correct or not, the only way I could make this work is to remove that rubber airdam. I also included a close-up.
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In these pics, you'll see that I had to drill a hole for the splitter's mounting hole to the bumper (the smaller hole). BUT, that bigger hole is for the bumper to mount to the car's under tray support, and figuring that mount is probably necessary, I had to (yep, you guessed it!) drill a hole in the splitter to be able to use a bolt similar to, but longer than, the OEM bolt.
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The splitter will come with seven bolt/washer combos for each of the seven holes, BUT three of those will have 3/4" spacers. I found that those spacers go between the splitter and the bumper in the middle of the bumper. You can see how in the pics below. This new air channel actually flows smoothly into the lower valence underneath the car, and might actually create a Venturi effect. Seems like it, anyway. Anywho, this is to say that creating the air channel does not allow air into the engine bay, and it does not create a choke point.
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Once all zipped up, it looks rather good! CAUTION: because you do not over-tighten the screws to the washers! The screw/washer combo is designed to be flush-fit (makes sense), but over-tightening can cause the washer to pop off (ask me how I know. 🙄). Luckily, I was able to get an identical washer for consistency, and was more careful than I was already trying to be.
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And here is a pic of the inside! I was concerned that the bolt length was too great, and interfere with the intercooler, but it's totally fine. There was a small fitment issue on reinstall, but it's simple to fix. See more after the pic.
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Okay, those bolts of the splitter were hitting a lower plastic shroud designed to channel air to the intercooler (denoted in pink). All I had to do was use a small flathead screwdriver to lift up that shroud to go over the tops of the bolts, and all was well. Simple fix.
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Sideskirts
Once the splitter was done and installed, I shoved some of the padding rolls up under the side of the car, and gently slid the sieskirt into place. These worked perfectly!
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This pic shows the rearmost edge of the splitter 1.25" from the outside edge of the front bumper. So, I tried to make the rear fin of the sideskirt match that distance from the body of the car, then zipped in the self-tapping screws. WRT to forward/backward movement, I found aligning the rear of the sideskirt with the inside edge of the rear wheel well, close to the exterior of the car, to provide the best fitment. However that aligned the frontmost edge of the sideskirt with the inside edge of the front wheel well, I simply positioned that front edge of the sideskirt to stick out as far as I wanted it, and duplicated that measurement on the other side. PRO TIP: use one of the screws as a 'tack': zip it into place just a little bit (1/8" should do), then position the opposite end of the sideskirt, and tie everything up.
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Okay, thanks for being patient, and reading thus far! Here's what you've been waiting for! Picture time!
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She's soooo hot! 😍😎

I would recommend this kit, for sure, but just know what you're getting in to. An official guide would be amazing, but not everyone can be Acuity, or Mishimoto, or 27Won, or PRL, or TEIN, or... Otherwise, my impression of this kit installed is just 🤯.

Now, RE the Greddy DD-R + the diffuser: there’s a small rattle only on start-up, but no other rattles while driving (which is good). My biggest concern was heat damage, so, I went driving for a bit to let everything heat up, then immediately pulled over to a parking lot, and felt around the diffuser near the exhaust. To my surprise, there was so little heat that I could rest my hand on the underside of the diffuser metal, just opposite the mufflers, and the diffuser metal was barely warm to the touch! 😅 I did this drive-test routine a couple of times, and it never got behind just a tad warm. So, that’s good! Seems like heat won’t be an issue, but just the vibration over time will cause excessive wear. I might try to find a flexible high-temp insulating barrier to put between the exhaust and diffuser, and will update as I go. For the moment, however, seems like a non-issue, thankfully. 🙏🏼
 
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