I just got the TWM w/ their bushing kit and had the chance to compare it to both the Kartboy and B&M on the weekend at a local meet. The general consensus was that the TWM was the best set up. The kartboy felt clunky and the B&M was really really stiff. The owner of that car said that...
No one has mentioned this so I thought I'd say that TWM makes bushings for the P5 now too and they're really nice...overall I think their kit is better that the karboy since the also use bearings in the shifter (makes for smoother shifts) and the throw is a little shorter. I PM'd TWM on this...