So this is the first time I've been asked this question and i think I'm a little stumped or this is the longest brain fart I ever had. But the question is my brother has Civic dx and is tuning up his D15b7. He has exhaust diameter of 2.5 inch piping but ordered headers (4-2-1) and a new hi-flow cat. But the the outlet of the headers are 2.25 inches and the so is the cat's inlet and out let. Now from what I've been searching and reading I believe everything with bolt up fine but, will it lose or gain power? going from a small diameter piping to a sudden 1/4 inch larger piping. I don't think it would lose power you agree?


Modified by NotAdelslow at 3:07 AM 12/27/2007

 

naaaw on an NA motor that amout of change wont be noticed. he will actually gain some more top end and lose a lil bit of bottom end is it. not really any numbers that are going to make a HUGE difference on a stock d15