hi all, im getting my car mapped in 2 weeks and was just looking at the japspeed 3" cat back exhausts, got a prodrive cat on with 2nd de cat so far, i know they are 2 1/2" but will there be any advantages or dis advantages by fitting the japspeed?
many thanks, shawn

 

The bigger pipe will flow better so there will be less back pressure allowing the turbo to spool up quicker. In December I changed my APS 3 inch bore exhaust for a APS 3.5 inch bore exhaust. The car is much livelier and gave a nice 40lb/ft torque increase in the mid-range with a bit extra bhp at the topend.

 

Hi Shawn,

it was my understanding that a 3" system isn't really critical till you start to push beyond 350+ bhp....

IMHO

dunx

 

I had a 2.5" system (including a prodrive cat) when I was running at 400bhp , so I guess they can't be too restrictive.