What kind of radio do you have? If you can adjust the endpoint for the throttle, then do it. That'll allow to control the top-end of the power, great way to keep you out of trouble, and learn the buggy on the track.

I'd run it 4 cells though, the buggy was designed to have that much weight in it, and you'll likely kill any 2 cell you put in it, unless you take it easy.