Ed, while a lot less than the NFGT, the '05 - '06 FGT has 500 lb of downforce at 180 mph (between 60-70% of that on the rear tires). That goes up with speed squared (so 617 pounds at 200 mph). If you get to watch the '05 in the 180 mph region plus it shoves the car down almost to the bump stops...