You could check out the ones that the RYCA guys are using too; several of those guys have complained that they are too loud, but if that floats yer boat....
They are made by EMGO, and any of their slip-on mufflers will work as long as they have the right inlet size for the header; I know MOTOBUDDAH flirted with a different style of emgo pipe.
Supertrapp also makes a few different models that will fit; again, find out the pipe size that you need to connect to and search that way; if you just look for LS650, or Savage, or S40 you won't find as much...
I got mine for free from my buddy Jay!! No idea what it is, but it looks awesome... bet it's going to be really loud too, so I'm thinking it'll need some extra baffling inside to calm it down.

If you are changing the exhaust and re-jetting it might be a good time to switch to a pod filter to take full advantage of the extra power you can get. There are tons of folks who have done these mods in the tech section, so everything you need is there to find if you just search a little bit...