Just read on IXXRA site that someone is selling a pair of Quill T3 Zorsts, states they need a power commander if fitted to a 'Bird with a catalytic converter, his is an '01 Bird.........he is selling the P/C in the deal. I have Quills fitted on an '04 bike, do I need a power commander with them? Not noticed any probs to date.As I understood it you only needed a P/C if you fitted aftermarket Zorsts AND a K&N filter? :dunno: