What's The Best Diameter For the Exhaust
 

I going to make a non cat, and non resonator exhaust. I'm just putting muffler and was wondering what's the best size piping for the 4.0L

Id say 2.5. Anything bigger then that and you will prob suffer powerloss. It also sounds great and has enough backpressure for the engine.

I think we beat this to death in another thread

Defintiely 2.5". Been working great on my XJ 4.0 HO.

X2.....

:head:......

I'd agree w/ the 2.5"... 2.25" isn't bad either...

2.5 is the best size for the 4.0 any bigger you will lose torque unless you turbo or supercharge there is no need for larger

Lets say I stroke the engine to 4.9L would it still be the same size?