Harry- I don't have the Corvette C6 in front of me to look at. I have no track time on the Sophia yet. So what I get is this. You have traction roll and the rear is loose on occasion. I suspect that the wing on the corvette was farther back. This does two things. It nails the rear down in the corner. No more looseness. And because the wing is behind the rear axle it unloads the front giving less steering for traction roll.
These are things you can do. You can move the wing back by using
HPI wing supports and moving the wing. It is some trouble as both the wing and the body have nubs. You may be able to move the stock wing back farther on the nubs. I am sure you could with new wing supports. You can go at least 1/2 inch back from the centered position. This may be all you need.
If you have too much front traction causing a traction roll, Remove steering throw at the radio (reduce dual rate %). Reduce front traction with stiffer front springs, Glue the sidewalls up to make a stiffer tire. or use a harder front if legal.
John