I have a D & D full system. I love it. It is louder than the muzzy. D & D pipes are the most free flowing and therefore the loudest. Only downfall is I had to trim the factory lower with a dremel (not a problem if you have an aftermarket full faring) and I had to remove my centerstand. You cannot notice where the lower was trimmed unless you look under the bike or remove it. I had to remove a small piece on the very bottom...it took less than an hour to remove the old exhaust, centerstand, install the new exhaust and trim the faring. (Rejetting took longer) It was well worth it in my opinion. I got it from www.parts411.com They have pretty good prices and carry most of the exhausts avaiable for an ex500. www.pipecity.com is another one. I ordered my jet kit from www.dynojet.com. With the settings recommended for stage 1, there is a HUGE noticable power increase and very little tuning was required. About all I had to do is adjust the idle.