As for the up/downpipe helix/perrin both are good brands.....For the exhaust everyone has their own opinion. I personally have the HKS Hi-Power and it sound freakin' mean!!!! But you'll pretty much get the rumble out of almost any exhaust because of our boxer engines... So dont worry..It wont sound like a CIVIC!!!
I been looking myself. I think the borla hush it too quiet if you really want a louder sound. Check out the bosal, also available in a dual tip, very cheap, and is more medium in the load/quiet spectrum