what type of sound? "turbo sounding". that's a quick fix. all you have to do is install say, a t4 front mount i/c, bov, wastegate, i/c/ piping, turbo timer.........
sarcastic one 'aint i? j/j
what kind of sound do you want? deep/quiet, most turbo exhausts are pretty loud, but that's because of the amount of exhaust gasses exiting the muffler, (it's a much higher rate and and greater velocity).
the muffler you choose will have the tone effect. also, some people choose to remove the resonator as well. that increases the exhaust tone level and changes it's pitch as well. i've heard removing it can give you a few x-tra h.p., but in all honesty, i don't remember seeing any review or dyno comparison to leaving it on or removing it.
my advice, get a quality cat-back. the big names like hks or greddy sound great and retain the resonator. thermal makes a system that sounds deep and very aggressive but it is fairly loud. guess you'd have to be more specific on what type other than turbo sound your going for.