I just test drove a 01 Cobra and when i was in gear and went to romp on it it gave a clunking feeling coming from the rear. A feeling as if say you were running about 30 mph in 5th gear and romped on it and it clunked due to low rpm's. But the fact of the matter was it was happening at any gear when getting on the throttle. It was fine however when you accelerated slowly. The dealer tried telling me this was normal but i believe otherwise. What could this be?