gt28r on b16a2
Would it make a difference if I change my dp from 2.5 to 3? I did my exhaust 3", but the dp is still 2.5. The guy at the shop said it wouldn't because I'm running 8-10 psi on a stock motor and the housing is small. If this was a t3 or bigger, doing a 3" dp would show results. True? not true? Should i get the upgraded dp or nay? Thanks!

 

I think 3 inch downpipe is the way to go, if your using a 3 in exhaust....