Sportmode

i was just wondering at what point does a 2.5 in exaust start hindering performance on a boosted b18c1. Basically how high can you boost with the same performance as a 3in exhaust.

bretx0r

it flows fine IMO. not too loud, and you can always add in an exhaust dump for the track

UberTeg

Realisticly, never. Its a fact 3" offers less resistance than 2.5" at any point in the powerband. And turbos rely on diffusion for part of their power... so the least resistance there is, the more power the turo has to spool up And a faster spooling turbo makes power sooner.

tony1

3" exhaust will make more power regarless of boost pressure. It will make more of a difference with more boost, but will be better regardless.

Diego Boost

Here's a good article on exhaust and boosting..

http://www.horsepower411.com/forum/s...d7e&threadid=6

SIK IN DA HED

works cool and not as loud as a 3in exhaust. of course the 3in is beneficial oer a 2.5in in size.

UberTeg

Great article, I remember reading that awhile back. It basiclly answers all of the questions asked here

Sportmode

what about if you have a 2.5in downpipe and cat, i know that with a 3in exhuast a 3in downpipe would be optimal, but if you are just running a 2.5in dp will a 3in exhuast still benefit you over a 3in?

now to read that exaust article....thanks for all the good info!

UberTeg

Yes, a 2.5" downpipe and 3" exhaust is better than a 2.5" downpipe with a 2.5" exhaust