First of all, make sure you're on perfectly even ground. Its possible that you bent the frame or a suspension arm causing that problem... a friend had the same thing happen in his civic. Take a very close look at your rear suspension and subframe, and if it looks ok, take it to an allignment shop and have them look through it. If that were the case, you would almost certainly feel a difference in the handling of the car. Does it handle like crap, or does it feel fine?