Quote Originally Posted by marquee View Post
Mine is 3" its not so much a forced induction its more the power pulling and size of an engine. Turbos normally have a 4" turbo back for optimum performance. Most engines like the bseries engine would use 2.5" unless forced induction was added. There is not much difference between 2.5" and 3" however if wishing to go turbo or for most accord euros supercharge or increase the power substantially then a 3" exhaust will be a much better building block however there is nothing wrong with 2.5"
Id be very surprised if you gained all throughout the rev range with a 3 inch system from the header back. Even though the 2.4 k series is a biggish 4 cylinder engine i dont think it would generate enough back pressure that a 3 inch system would then alliviate.

Back before i had the dc2r, i was getting around in an S15. 200kw at the wheels and the system was just 3 inch. The k24 is lucky to push 110 at the wheels....so 3inch is overkill.