Worst case scenario....put on a resonated x-pipe. That's basically an x-pipe inside a muffler. As far as they know...that is your muffler.
It should sound the same if not better if you remove the resonators when you install the x-pipe.
I have some video clips in this thread so you can get an idea of what it sounds like.
http://www.camaro5.com/forums/showthread.php?t=64964