No one really mentioned the best part about that pipe, IT LOOKS AWESOME!!! Screw the minimal gain/loss that may or may not be had with it!
The accordion pipe looks like a flaming pile of shat next to the BAT pipe! I'm a BAT pipe snob now. I can't look at an engine without it and think good thoughts (kidding).
Had to say something for the all show no go crowd.

Oh, and just for another opinion, I didn't feel any difference with mine, all I have is the KKM though, stock exhaust.