Originally Posted by Pokinacha
Best bet would be to enlarge the centre muffler (assuming there is one). the bigger the muffler, the less noise you get.
I doubt he's got a centre silencer (muffler). I would imagine there's a straight pipe instead of a cat, a straight pipe instead of a centre silencer, and then a silenced backbox on the end.
In this situation, I would replace the de-cat pipe with a silencer. Hopefully you won't lose too much of the crispness that way.