I ordered an R&D Power Pump (it replaces the accelerator pump cover and also includes a new stiffer spring for the AP linkage). The biggest advantage for this thing is that it includes an adjustable leak jet. Installation: You have to punch out a check valve in the float bowl (which has to be removed). This is easy, but I'm not sure how easy it would be to get the valve back in if you want to go back to stock. The original leak jet is removed and replaced by a plug. After this you just replace the AP cover with the power pump and adjust the leak jet to your starting point. The stiffer spring was no problem to install either. It takes a bunch of force to get the rod out of the linkage(which you have to do to replace the spring) and I was afraid something was going to break. How did it work: I mainly wanted to adjust the leak jet to get rid of an "anti-bog" or whatever. When I just open the throttle a little bit, the bike wanted to snap into action a bit too eagerly in my opinion. On sand tracks and in ruts this was no problem. On a clay off-camber, it was a slight problem. Not enough to even make the rear slide, usually, but enough to make me open the throttle a few meters later than I thought I could. I adjusted the leak jet as per the instructions to be a bit leaner than stock(55). I only rode once on a sand track, but I think that the results were definitely positive. I felt no snap, but no bog or any ill effects either. If I really twisted the throttle open, the bike did have all the bark it had before. I will post more once I get the the harder tracks.