Hello friends i have a JDM B18C and occupied change the exhaust, which is the best diameter 2.5 "or 3".
Diameter which gives the best performance?

Thanks

 

3" for top end. 2.5 for mid range I believe is the current belief.
Depends what the car is going to be used for. How loud you want it and all that.
Ill say it now though. Try doing a search in the all motor forum. Im sure this topic is probably covered atleast once a week.