Just out of curiosity, why do people get Cat Back and Diff Back exhausts? Does it actually do anything performance?? I think all that gives you is the boxer sound.

I say if you're gonna do it at all, do it properly the first time.

Get a Full TBE System and Up-Pipe too. Might cost a bit more, but the point of doing an exhaust is not only to get the sweet sweet boxer sound, but to get some extra KW's too !!