Theoretically, a very low 9 and possibly a extremely high 8.
I was tinkering on the car today and made a discovery. Because I have no support under the front nose, It's starting to get pushed in at those high speeds. The evidence is the front of the front fenders are being pushed out and it's already cracked the fender lip. I can easily fabricate some supports for the fenders to hold them in, but I'm going to have to make some sort of structure to hold the bottom of the nose outward. Pushing on the top part of the nose isn't bad but I can really push on the spoiler and push the nose under. The alternative is to buy a fiberglass nose.
Look at the nose and fenders on this truck. It's also running 220+ mph. I'm pretty sure my car is doing the same thing. I guess the up side is the spoiler is becoming a stripe taker at high speeds.
Wish I had video from outside the car to watch it myself. This was the best of 3 passes.
