While I'm very happy with TORs, I do like the sound of the Staintunes. Can't comment on power because Hanso won't let me ride his bike - just kidding; I know he'd have no issue.
Probably only downside is that they're stainless and therefore not a perfect match to the chrome heat shields and seem to discolour. I could be tempted to swap mine over but not if it was going to cost a lot to do it. Bike runs better than I ever hoped with TORS anyway and I'm happy enough with the sound.