i have a an Ashley 4 branch also with the De-cat.

i have a high lift cam, will be fittin my golf afm and now a coil and amp.

i already have a poloace chip with raised limiter ....

Noise is not a issue hense the reason for me deciding to take out the mid siliencer..

i quite like a loud car.

but my main query is what specific bore is best for performance wise on my GT?

2" should be plenty.

2.5" would be a bit overkill, especially without a centre box.

no more than 2" for definite

ok thanks it sounds find... but the standard GT exhaust is 48mm 2" ?

i thought about sizin it up a few mm?

or am i wastin my time...

or is it simply i will have plenty freeflow simply by 4brancher and de-cat?

2" is 52mm roughly. 2" is AMPLE on a small engined normally aspirated car. if you go any bigger it will be a waste and could actually mean youve got less power

Agreed, may not have enough back pressure otherwise, especially with no centrebox.

Remember, your backbox will be most likely be a de-restricted style affair as well (if you're going to longlife or someone)

2" bore should easily see you up to.. what... 130bhp? Without being a power bottleneck!

if not more from a normally aspirated engine. only FI cars need to go bigger to say 3" as they dont require as much backpressure to make good PS

well its in garage now as we speak gettin the two" bore..

so thanks for all advise...

I'm greatfull... and cant wait to hear it !