Well, I am going to let you all know that I have the problem as well. It kicks in around 75 and it makes me want to slow down. Today, I did turn off the traction control and it was not as bad. I am not sure if this is the answer to our problem and I am sure it is not, but it did reduce the vibration by about 20%. I will be taking it to a different SVT dealer Monday (original found nothing). Will keep updated.