I have been looking at the GTM's for over a year now. They really aren't a kit car in the sense that everyone thinks of. The red car you have pic's of is a prototype car, here is the preproduction car that was at SEMA this year.
They do use a lot of C5 parts and a Porsche G50 tranny from a 911. The tranny is the weak part, but there are a few aftermarket trannies coming to market soon. Both are capable of at least 650 ft/lbs and one is under $10k.
This car will be my next toy. I actually had a thread about it on here before. With a stock LS1 they got high 11's in the 1/4 mile on street tires. They have a LS7 from the new Z06 vette mocked in one and are expecting mid 10's.
If anyone is familiar with a Noble or Ultima, this is a similar type of car. It has been wind tunnel tested and it produced more downforce than a Ferrari 360 at 150 mph and basically the same as the Porsche GT! Frame stiffness is supposed to be the same as a NASCAR. It uses a custom suspension from Koni.