If you want power man you'd want a catback system with headers, but that is expensive. If you want something that is going to give you a little more power and response, then look at buddyclub, apexi (which yes, are around $400 odd for a muffler but they last and are made properly), remus and some magnaflow mufflers. If you buy cheap you will get cheap. EG: Buying a $50 cannon from supercheap will, in most cases, make the car even more unresponsive and you will lose power. I know a guy who's running an apexi N1 cannon, it's loud but you can suppress it with a silencer if you wish (he finds that it is fine without the silencer). Additionally, if you want an oval shape muffler that is still unrestrictive (but not loud) and flows nicely look at the Apexi WS2 muffler. ;)