I went with a FMF Powercore4 slip-on, Uni-filter with airbox lid removed, and a 170 main jet. Took it to Buttercup this weekend, It ran great. I could feel a noticeable difference in bottom-end and midrange power, the top end power is about the same, but overall, it gave me exactly what I was looking for, just a little more grunt. I may go with the RWR CDI in the future, but for now, it's making all the power I need. I can now run the Old Mexico trail, which has some interesting banked turns, elevation changes, and switchbacks, almost it's entire length if 4th gear, with the occasional fanning of the clutch. Stock, this was primarily a 3rd gear, with an ocassional shift to 4th gear ride.