Rumor is the SCCA will not classify the C6 Z06 in T1. The 500 HP Viper has been out for a few years now and it is not legal either.
No one yet knows how the C6 will fair against the C5 Z06. I think they will be close enough that the C5 Z06 will be competitive in T1 for several more years.
While the C6 Z06 looks to be an awesome track car, especially for the cost, if it really does have an aluminum frame, plan on spending some serious $$$ if you wreck one.
