2.5 vs 3inch Downpipe

Cant find a discussion about this, was wondering the pros n cons to each?

Pro for 2.5" is it allows for more consistent flows for these smaller 1.5t and thus better mid-range power than 3", basically no scavenging for 2.5". Con is 2.5" mandrel bent only go up to as high as roughly about 450HP before being a bottle neck where as 3" practically has no limit of power.

LightX said:

Pro for 2.5" is it allows for more consistent flows for these smaller 1.5t and thus better mid-range power than 3", basically no scavenging for 2.5". Con is 2.5" mandrel bent only go up to as high as roughly about 450HP before being a bottle neck where as 3" practically has no limit of power.

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I read that somewhere else not sure if it was on here but some didnt believe it but that scavenging effect makes complete sense to me. Funny how alot of people make it a big deal when they get a 3inch fp n dp, some even have switched from 2.5 to 3 looking for a performance increase, when its only getting louder lol

Wouldn't a 3" dp/fp into a 3" exhaust (3" back from the turbo) help the turbo spool faster?

Speedy02 said:

I read that somewhere else not sure if it was on here but some didnt believe it but that scavenging effect makes complete sense to me. Funny how alot of people make it a big deal when they get a 3inch fp n dp, some even have switched from 2.5 to 3 looking for a performance increase, when its only getting louder lol

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FR32H OJ said:

Wouldn't a 3" dp/fp into a 3" exhaust (3" back from the turbo) help the turbo spool faster?

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Full 3” dp/fp will lose power in the front pipe. I mean have you tried running just the downpipe only haha. Your car will be slow like a Prius. That’s exaggerating but the difference in power is there. Back pressure is required for optimal velocity and efficiency of exhaust. Turbo will spool faster as exhaust exit quicker at a higher velocity. Which is why turbo blanket will also help with the spool because hotter exhaust will exit at a higher velocity, full 3” is just a tad bit little too much scavenging for 1.5l displacement.

I had tried both I found that 3” dp 2.5” front pipe stock exhaust works best

jami3xxx said:

I had tried both I found that 3” dp 2.5” front pipe stock exhaust works best

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What brand dp/fp did you use?

OceansX said:

What brand dp/fp did you use?

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I had rev9 then got prl as I learned more about these cars but I kept the rev9 fp works good

OceansX said:

What brand dp/fp did you use?

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jami3xxx said:

I had rev9 then got prl as I learned more about these cars but I kept the rev9 fp works good

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how was it when you had the full rev9 setup? (sound, performance)

I looked them up, pretty budget friendly on ebay.

I also have a ktuner on the way.

Well I have a cvt first of all I’m sure manuals feel much better Ive modded lotta lotta cars so I’m pretty good at the feel .. rev9 is just fine tbh it’s like maybe 5 hp peak less more low mid range it’s cheap 200 bucks but I’d spend the extra money to get a better dp even 1320 is a lil nicer and 3” 250 bucks .. if you want to make it more stealthy get a prl v2 or rv6 so you can use your stock heat shielding

OceansX said:

how was it when you had the full rev9 setup? (sound, performance)

I looked them up, pretty budget friendly on ebay.

I also have a ktuner on the way.

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I just got my ktuner today set it at 21 psi it’s ok .. maybe 20hp it’s not like ur gonna go holly crap if you want to really feel it get a custom tune dial everything in ..

jami3xxx said:

I just got my ktuner today set it at 21 psi it’s ok .. maybe 20hp it’s not like ur gonna go holly crap if you want to really feel it get a custom tune dial everything in ..

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Thx just really lookin to keep up with the stock SI's and VW's

OceansX said:

Thx just really lookin to keep up with the stock SI's and VW's

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Need a e tune , heard this dude is legit http://www.e-tunez.com/services/2016-honda-civic-turbo-l15b7-inc-si-racenon-carb

jami3xxx said:

I had tried both I found that 3” dp 2.5” front pipe stock exhaust works best

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'Worked best' as in....

jami3xxx said:

Need a e tune , heard this dude is legit http://www.e-tunez.com/services/2016-honda-civic-turbo-l15b7-inc-si-racenon-carb

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Unfortunately we've seen more than one "questionable" 10th gen Civic tune come from e-tunez.