I was searching around last night and found this company, i don't know a ton about it, but i know that it mounts without straps which some people will like, but it looks like they are similar to Scorpions, and they sound decent. (You tube video)
Cool Reiobard, that thing is the cleanest one I have seen yet and it is 2lbs lighter than stock. I like the roller run data too as they are showing roughly 6hp increase. Check this out: