@Jake - it's much better now than in the video, even though I had only 3 balls in the clutch then too. Carb was too rich in the low end. Switching from the stock SHA filter to a foam insert, plus drilling holes in the black plastic filter cover (then rejetting accordingly) really allowed it to hit the sweet spot. I am very happy with the overall setup. I think with different gearing I would easily be in the mid-50's, but I don't want the extra lag off the line.
@Charlie - the kit I'm using is the gila 50cc. Although the simonini had nice midrange and not too bad low end, it really ran out of steam at the mid-high rpms. I think the G3 is better suited for this kit, though the simonini would probably be better for stock.