What diameter is best for a b18c

[Chris_EK4]

Hi, I'm getting an exhaust made for my ek4 on Monday, as I'm fed up with aftermarket ones not fitting properly, my car has performed best with a buddy club pro spec (snapped in half...) I have a 2.5" 5zigen pro racer a spec ATM but its not as quick as it was, even though its running a 2.5 collector now and before was running a 2"?

Is 2.25 or 2.5 best for a b18cr? What have you seen better performance with?

It's stock internally with a few basic bolt ons, 202bhp

Thanks

 

[pedro_rallye]

the JDM size 2.5inch is better

 

[kulo]

2.5

 

[firebass]

yeah i have tested both 63.5mm and 70mm so far 70mm with no catalist and middlebox is the best until 3rd stage bolt on stuff

 

[Curtis.]

My b18 was breathing happily @213 bhp with a custom 2.5" system.

 

[tama666]

2.5