Originally Posted by twinturbomeow
would'nt a sti axleback create a bottle neck considering he's going from3" piping to 2.5?
From what people have tested, it really depends on the size of the turbo he's running. If it's stock or near stock, doesn't really make much of a difference.
To OP: the stock STI axleback will be the quietest and will mate up fine. IIRC, Grimmspeed has a flange to get aftermarket downpipes to mate with stock axleback easier. It'll be the cheapest and quietest solution