Evening ,

Noob here .. Own a NA accord f22b2 . I have a lot of bolt ons . Only internal changes are going to be Bisimoto Stage 2 Cam ..(maybe it's finished ) . I have replaced the flywheel with a 7.5 lb Fidanza and Exedy clutch . Is is safe to run 2.5 inches ? Or does it need to be more like 2.25 . I don't like Magna flow or Apexi WS2 .. eventhough they are recommended .I don't care for top end but would like to be low to mid for increase in response .

Thanks ,

 

Yes its safe to run 2.5 but you might see a mild loss in scavenging, probably not enough to notice though.

k.

 

with a 2.5 you will lose a lot of low end and gain some top end
honestly, 2.5 is overkill for N/A F22/F23
try 2 or 2.25 and you should be fine. keep your cat or you'll lose more back pressure
custom exhaust FTW although my custom exhaust consisted of Magnaflow parts

 

Well I bow to your specific knowledge of these engines but losing back pressure is not the root of the issue one way or the other. Thats one of those internet myths that just wont die. Back pressure is not a good thing - ever. What you want to do is size the exhaust such that it maintains the best possible compromise between minimizing back pressure but elevating exhaust velocity such that the moving volume of air in the exhaust acts as a type of aspiration pump on the motor.

k.