I've seen an article where someone just took off the resonator and built their own Y-pipe in place of the resonator.
You get to loose one of the restrictions in the system, loose some weight, add some sound, and keep the stock muffler/tips.
Some day I'll probably go this route, but right now I'm content with the stock sound, keeping it quite like a sleeper.

I like making fools of loud and obnoxious Mustangs and Camaros that try and race me.