I have the Leo Vince w/cat eliminated and a K&N filter, with out using any type of fuel management system. The only drawback, as mentioned by other members, is some slight backfiring/"popping" with the throttle in the completely closed position. It's not enough of a problem to justify spending the cash on a power commander. Although I do know they will do more things for you, but honestly, there is not enogh of a straight road where I live to open it up the way it's set up now, let alone with even more HP. MATT