Sport Touring Factory Sub Upgrade DIY

dj2819

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The Acura TL that I had before my Civic had a 600w Type-R sub which sounded amazing. Even with "premium" audio in my 2019 Civic Sport Touring, it is not that great. The website has the wattage advertised as 75w but who knows if that is RMS or what. I followed this guide of a 2016 Hatchback factory subwoofer swap. Since it seemed relatively easy I did it and took some pictures so anyone else can do a quick upgrade. There is also a more detailed guide on how to upgrade the factory sub with an amp and LC2i. I didn't want to void any warranties so I did not choose to do that yet. So here we go:

Parts Used:
Rockford Fosgate Punch P3SD4-8 Shallow 8" Dual 4-ohm Subwoofer (from Crutchfield)
Poly-fil Premium Polyester Fiber Fill
Male/Female Bullet Crimp Terminals 16-14AWG
14AWG speaker wire
Gorilla Tape

Tools Used:
Trim removal tool (or be careful with a flat head)
Phillips Screwdriver
10mm Socket Wrench and extension
Wire stripper
Wire crimper



Steps to remove
  1. Clean trunk out of any items or mats. The trunk floor panel will be removed.
  2. Carefully pry open the cargo hooks on the trunk floor panel. Remove the Phillips screws from both hooks and set the screws + hooks aside.
  3. To the side of where the cargo hooks were, there are two clips holding the panel down. Lift up to release the clips and remove the panel.
  4. Carefully pull up the hatch door scruff panel. There are 4 clips, spread evenly starting from the bottom edges. Release the clips and remove the panel.
  5. Remove cargo cover assembly if there is one equipped. Slide the cover back into the assembly and slide the latch up to remove.
  6. Remove the screw cover that is in the cargo cover bracket. Remove the Phillips screw and set aside.
  7. Pry out part of the gasket from the rear passenger side. Only enough needs to be removed so the panel can be removed.
  8. Pry the rear side panel out carefully. There are 4 clips holding it in place. It only needs to be moved out of the way so you can access the sub enclosure, it doesn't need to be removed fully. Be careful of the back of the panel, there are clip/notches that break easy. When I put my panel back in I noticed that one of them were bent. Also when removing the panel be careful of the light connector. It needs to be removed.
  9. Remove the 8 screws holding the trim ring in place and remove the ring. I didn't end up using this in the end, maybe it can be re-used? I am not sure.
  10. Remove one 10mm nut (might need an extension and the 3 10mm bolts. Disconnect the harness and remove the enclosure from the body.
  11. Remove the Phillips screw from back of the enclosure to release the factory sub. Remove the factory sub from the enclosure and disconnect the speaker connectors.


Steps to install new sub

  1. Tape the hole from removing the Phillips screw using gorilla tape on both sides. This is to ensure that the enclosure is sealed. You could use silicone but if you want to run speaker wire later through the hole, then you have to remove the silicone.
  2. The sub I used is 4 ohm. The system is 2 ohm I believe. Actually I am not 100% sure so maybe someone can clarify below but in the YouTube video I was following, he wired the new sub to be 2 ohm. Basically take your speaker wire. Cut enough to connect from one positive to the other. Repeat for the negative side. This will make wire the 4 ohm sub to be 2 ohm. This can be verified by using a voltmeter in the Ohm setting and checking if it is 2ohm.



  3. Cut enough speaker wire to connect from one set of the positive-negative terminals to the speaker wire in the enclosure. Attach the bullet connector to the end of the wire and crimp. Also do the same for the speaker wire in the enclosure. I used opposite types for positive and negative so when connecting, only the correct polarities get connected.
  4. Lightly fill the edges of the enclosure with Polyfil. This is said to make the sub feel like it is in a bigger box making the sound travel more. Polyfil is pretty cheap so I went ahead and did it. Not sure what the difference would be without it.
  5. Connect the newly crimped sub connectors bullet connectors to the connecters in the enclosure. Use the 8 Phillips screws removed from the trim piece to mount the new sub on the enclosure. With this Rockford sub, the screw holes should match perfectly without drilling any new holes.
  6. Follow the removal steps in reverse to put everything back together. I would screw in the enclosure, connect the harness back and then do a small test to see if the sub is working correctly. If so then put everything back together.

That is it, it is a pretty simple install. Removal of the trim is also pretty easy. I bought my sub for $150 + tax so I think it is a great upgrade for the money. The bass sounds deeper and a little nicer. No where as nice as installing an amp but it is a start.

Let me know if you have any questions or if anyone else upgraded the factory sub with different aftermarket brands. I was considering the Alpine Type-S, if anyone had that installed let me know how they like it.

Original video that I followed to do this swap:
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kperalta

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This is dope lol. I wish the sedan sub wasn't free air
 

Boosted1one

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Oh man this is awesome. You guys have an actual "sub box" to work with. Wish it was this easy to swap out the pathetic Si sub. (Honda must have saved loads by making sure every single person will say "what sub?" Sigh.

Can't utilize it but nice write up! I miss seeing these era type write ups!! Photos+instructions!!

Can't this YouTube gen crap, just gimme the darn step by step instructions! 1, 2, 3, 4. Not this nonsense oh go back, more, forward, wait what he say. Nonsenee.
 


ilipac

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Is it possible to wire up an additional subwoofer or a better one directly to these sub wires? I have an opportunity to get a Rockford powered one and it would fit right in my trunk
 

Phy

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Is it possible to wire up an additional subwoofer or a better one directly to these sub wires? I have an opportunity to get a Rockford powered one and it would fit right in my trunk
Technically, yeah, but the problem with the factory system is the factory amp. You'll get much better results pulling a signal from the front door speakers and using an aftermarket amp.
 

ilipac

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Technically, yeah, but the problem with the factory system is the factory amp. You'll get much better results pulling a signal from the front door speakers and using an aftermarket amp.
LAMEEEEEEEEE lol, I’ll try it with factory wiring and see what it does
 

ilipac

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Technically, yeah, but the problem with the factory system is the factory amp. You'll get much better results pulling a signal from the front door speakers and using an aftermarket amp.
is there an ability to splice in at the headunit?
 

Phy

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is there an ability to splice in at the headunit?
You have to splice after the factory amp, but it's the same procedure, just a different location
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