im looking to take my car as close as i can to the 400bhp. currently im running at 340 bhp. i have bought the neccesarry mods i.e turbo, injectors, headers and getting some Andy F magic. the only question mark would be the exhaust system i am running. I have a magnex twin dump decat, and a blitz nur spec cat back system is this free flowing enough to support 400bhp....?? any help appreciated

 

General rule I've read is 2.5'' to 350 and over 350 use 3''

My Sti runs 380+ on a 3'' (also with AndyF magic!)

Graham