I'm getting cutouts, so I don't have to worry about getting it routed or anything. I'll just keep it with the stock muffler, since cut-outs won't need a new muffler to be louder than every other car on the road.
If I were you though, maybe look on Ebay or a trustworthy internet site, or there are even some places out in Mesa that give pretty good deals on parts, but go with Gibson. They are reliable and less likely to leak. They know what their doing with truck exhausts. If you want the cool styling of a dual exhaust, they sell a sort of dual outlet, it's just two pipes sticking out of the back of the muffler, you could get some nice chrome exhaust tips and make that look really sweet. Borla, Flowmaster, the usuals would be good too, but I wouldn't suggest trying out some of those cheaper, less used brands, just not as safe bets on reliability.
