Before you spend on an aftermarket exhaust, try a power tip first (this mod is better if you put on a K&N or Durablue air filter at the same time).
some people drill out the baffle using a long drill bit with a 12mm diameter, they normally put about 10 holes in the baffle. I on the other hand, cut my standard exhaust in half, and removed the bafflles etirely!! then welded it back together. Iput on a 2" tip and the beast really sounds deep/loud and mean!! like it should.