If you want it to stay at least legally loud, get a straight-through muffler like a Dynomax or whatever is similar. Flowmasters may sound alright, but alot of mufflers have surpassed them in performance.
I took the muffler off of mine and put a 3" side pipe on it coming off the cat (which is stock with the down pipe). dosent sound like rice, and you can hear the turbo very nicely while idling and not too loud. Just right for me.