This was done at a Viper event I attended last Monday. This is a Toyota Supra running I believe 17 psi. He was very, very, fast!
http://www.tbe.net/~supra/video/PoconoLongCourse040802/

 

Great video. The first banked turn following the start/finish line looks deceptively easy on video. In reality, it's a heavily banked, white knuckle adventure I take at about 110mph in my ITR.

Bits of rubber slamming into the fender wells and that wall LOOOMING on the right add to a sense of pending disaster.

 

That Supra is SICK fast. What kind of speeds was he hitting down the straight?

 

Amen, It was a little hard pushing the car when there is an unforgiving wall right next to you on the right. My speedo said I was hitting about 142 on the back straight, so that Supra had to be doing at least 160-170 maybe more. I did change the stock rims for lighter 16X7's that would make the speedo register a slower speed than you are actually going right?? Then again you have to factor in that the speedo isn't really all that acurate at those speeds anyway. In short your guess is as good as mine.