get a dynomax bullet race muffler and mount it
right after your cat.
it will quiet things down a lot.
i noticed that couple of you recommended a silencer.
i just dont see the point of having a silencer. what you do if you do come across someone that wants to have fun (race

: on the highway??? what do you say?? "oh...let me pull over so i could take my silencer out"
hell no you step on it a kick some ass.
you need your exhaust to be quiet untill you really get on it 4000rpm+