Hi quick question on the earlier v8 Sti jdm vf37 cars they had a single cat down pipe with bellmouth entry as standard can these down pipes make around 335hp 350ft with a aftermarket cat back ? Or do they really need a 3inch down pipe ?
Regards.

 

I'm on a later vf53 twinscroll, still on oem cat and 2.5" exhaust, dynoed at 359bhp, so can't really see why not.

 

Thank you.

 

Just to clarify, that's with a panel filter and a fuel pressure regulator upgrade, and the actuator was upgraded to hold boost.

 

should be no issue at all.........std cars will make 350+ with a custom map

 

Any one know where you can buy a decat twin scroll with a 2.5 donut style fitting and the cat back end?
all the Rcm and millteks are 3inch flat face flanges.
if not il just use the stock oem single cat . Didn’t realise the oem cat was a bellmouth style not like the older single scroll that are plate with just one hole.

 

I think h & s exhausts sell one for about £300

 

Nice flat curves. You won’t get more until you decat.