Mugen is nice if you can't deal with much noise, and don't care about weight savings and HP gain... because you won't really get either. It's one of the heaviest aftermarket exhausts, and has no dyno proven HP gain. Many get it because of the name, or because they can't stand the dBs from a single... think about it, s2k is a four cyl. one header. two pipes are purely cosmetic... Real power adder is something like an amuse... check out
www.bulletproofautomotive.com and look through the exhaust section...