If u have the dough get a catback, but its not a big deal it doesnt increase HP by much. About a month ago, I had that rusted stock muffler and I took it off, and had my boy weld together a magnaflow str8 pipe NO cat or res. Its pretty loud but sounds really nice. Its deep at low RPM then at about 3,500 it sounds like RAPE. Anyway get muffler to hold you untill you can get a catback or if you have cash just get the system. Also ebay have some decent catbacks, they will sound way better than a rusted muffler and their pretty cheap.