Most on the time im very easy on my jetta, but when I am driving it really hard and i acelerate hard theres an intial knocking sound at the beigning of first gear, then when i go into second and sometimes when i shift to third. This is when im shifting hard, im wondering what this is. Ive gotten a few sugestions that maby its wheel hop but im not sure. Its making a sound that sounds like someone was under the car knocking on the frame. dose anyone have any idea what this could be? i would aprciate it.