I have installed an 03 cdi on my 09 and my son inlaw installed an 04 cdi on his 09. We both first installed a Dr. D pipe, Rekluse Pro and then an 06 cdi. The 03/04 seems to hit harder than the 06 we had on our bikes and still maintains a good top end. It hits like a 450 should when you twist the throttle. The 03 cdi is my new favorite cdi on my 09.