Alex,
Thanks for the input. I think I will have the tires balanced, and if they are shot, I have another set. BTW, there is only vibration, but no noise (other than the car shaking itself to pieces!!!). It is pretty massive vibration, and I've ruled out drivetrain stuff, I think, because it is road speed related, not engine speed related. It revs beautifully to redline, without donut-issues (it a GTV6 BTW). I will poke around underneath the car though, to look for other possible causes.
Thanks again!
