if your "hd" rear wheel untrued itself, then there are two possibilities. One is that the sprocket is not installed correctly. I have done this myself on my first bike, so dont feel bad if you did. The other possibility is that your wheel is not all its hyped up to be. As far as a better sprocket, the 44t sprocket that comes with the kit is good for acceleration and moderate top speed. as far as "not running wide open", one, ease up on the throttle. you can also release the throttle and pull it back again repeatedly. I used to do that and it helps a lot with gas mileage. two, higher gearing will actually put a little more stress on the engine (not much, but for longer engine life, lower gearing is better), and it will make you go FASTER. By higher gearing, I mean a sprocket with less teeth. by lower gearing, I mean a sprocket with more teeth. more teeth will give you a slower top speed and take more stress off the engine. but again, 44t will give you better acceleration, and depending on your weight should give you a top speed in the neighborhood of 30mph. I weigh 280, and with a 44t sprocket, my top speed is right around 30.