I had these on my car for just over a year and they helped me cut very consistent 60ft times in the high 1.3s.
Except for some cosmetic scuffing they're in great shape. The only reason I'm selling them is that I replaced them with double adjustables while trying to troubleshoot a traction problem, which later turned out to be caused by a minor problem in my transmission tune. I briefly thought about putting these back on and selling the doubles but felt they would be the better approach since I race as often as I do.
I'd like to get $200 shipped which is just over half the price of what it costs to buy them new (when you add in shipping charges). Please note that although I had them on my C6 they will also fit on a C5.