I know a lot of people who hate on Flowmaster. Don't know why. For me, it's all about tone, and I think Flowmaster has the best out there. I love mine, not quiet, but not loud enough to attract attention, just a nice deep rumble tone to it, no popping or droning.
Right now I just have the stock headers, and I believe it's a cat-back Flowmaster system. Single outlet coming out behind passenger rear tire. My muffler is HUGE, but I don't want to change it, I love the way it sounds. I've been going back and forth on what I want to do for headers, shortys or long-tubes, but that's a different story.