Swampy,
It sounds like you ride your bike a whole lot harder than I ride mine. This is my second Blackbird. On my first I never changed out the pipes. On this one, changing out the exhaust system is one of the first things I did. All I can tell you is that you will not believe how much better the bike performs with an aftermarket system. Have you ever felt that slight hesistation when you roll on the throttle before the engine responds? Well, after installing my pipes, I feel no hesistation. Also, I just seems like the bike wants you to open her all the way up with the aftermarket pipes.
Maybe you shouldn't get them; they way you ride, you'll probably hurt yourself with all that extra performance.
By the way, I installed the Yoshimura RS-3 Race exhaust system. And, no you don't have the install a power commander for it to work (although I know I could squeeze a few extra HP if I did). MPG: 32-33.
Joe