Exhaust diameter

[ceebies]

Simple question. Im getting a custom system made, anybody found any information on the best size for a R?

[Paradox1]

If your getting the full exhaust done, then 3inch is sufficient. you can go 3 inch all the way to the back box which will probably be the best for flow but not essential. some taper down to 2.5inch which still get decent gains

[ceebies]

Yeh figured 3 inch, just concerned about sound. I dont want to be that dumbass with a WRX milo tin which sort of sounds like a sick cow when they take off...