Just noticed today, have a decat pipe which is 3inches+ bore, but at the flange where joins centre section its only 2inches, my middle section and rear box is all 3inch bore, how much power loss is that going to cause if the decat to middle section flange being 2inch!? used different ecus and turbos but never made much more power differences on a dyno, could this be a good reason?

Cheers

 

no. for standard setup it makes little odds going from 3" to 2.5". only when you start making some power will a full 3" from turbo back make a difference.

 

As above,on mine it made a difference once over 400bhpwith the 2.5"join it made 420 then With 3"all the way it made 445bhp

 

im running 400bhp, and is 2inch at joint not even 2.5inch

 

Change it to a 3" all the way it will transform the car, mine was to join to a 2.5"system so was a bit less than that as it fitted in side.once 3" all the way made more power and the eng felt like it had been let off a lead