ive had my Si for like 2 days going on, i came from a 2002 mustang gt. Ive been reading a lot about the Si. From what i have read, i take it exhaust systems really dont do too much for a pretty much stock Si? What is a good exhaust, i dont want anything terribly loud either. I want something that is good quality, not to huge to where i lose back pressure, and has a decent sound. If it also adds a lil power would be great too, any suggestions?