Leedom,
The only factory suspension pieces on my car are the sway bars and the A-arms.
I have the braus harness bar (only one crash certified) and five point harnesses that I use when racing. Due to the hoop behind the driver the silver state classic rates the c6 to 125mph with no additional safety equipement. With tha said, I definately do not feel comfortable at 165 in a turn in a stock vette. I don't think that a crash at 145 would have any different outcome though. Reducing the speed reduces the likely hood of lossing control, but a crash at those speeds would be severe even in a NASCAR cage. The has aftermarket rotors and pads, but unlike drag racing as you learn a track the difference in speed and momentum are much more extreme which requires the driver to constanly adjust braking and turn in points which changes the line.
But just like drag racing the whole purpose is to see how hard and how fast I can make it around this track (safely).