Now this is just a wild guess but you must have a TD rabbit. I've heard the turbo acts like a muffler of sorts.
...BTW your Bieber avatar is awesome.-Malone
a TD is NOT loud. i dont care what anyone says. run a n/a with less than 2 feet of exhaust coming off the head. it would really get loud when i would roll the propane on.turbos ARE mufflers!