exhaust pipe size
 

ive just bought a 3" exhaust and its the backbox and a center section, it was advertised as a cat-back exhaust.

my question is i have a 2.0 sti type uk 2005 model, will it bolt right on to the pipework thats there? as thisnew stainless pipework looks a bit bigger?

standard downpipe cat is 3" at turbo end down to 2.5". Mid cat pipe is 2.5" to 2.5". if it's a true 3" cat back system then the centre pipe will be 3" to 3" so it won't fit.

you'll either need to get a 2.5" to 3" centre pipe of just scrap the 2 cats with one 3" pipe that goes from turbo to centre pipe. Cobra sports do one for about £135.

http://www.cobrasport.com/images/products/359.jpg

Cobra Sport - WRX STI 2001-2007