I've got a hyper 7 and don't know if I should go .21, or higher. I have the original hyper .21 but was wonderind if a .28 with taller gearing would be faster. And if it is faster will it hurt the diffs in the long run. I'm "racing" but not "RACING" (we made our own track in a lot nearby[>:]). I'm not new to the hobby, but I am new to nitro. Any help would be greatly appreciated.