Muffler selection

It sounds like Rumblefish is giving you some more sophisticated advice than what I have to offer but I would also encourage you to find some videos of different styles of mufflers too. It's always hard to tell exactly what they will sound like in person (because of the uncontrolled audio recording conditions, etc) but you can get an idea of the general quality of engine sound you can expect.

I have always found Flowmaster/chambered mufflers to offer a boomy/hollow sound. Personally, I don't love it but lots of people do. The Magnaflow/flow through types tend to be a bit more raw/natural sounding IMO. It's probably worth your time to take a listen.