What he said. Looking to 'keep it real' hahaha. However, we may try to expand and see if the Ford GT can be upgraded within reason. The problem you run into with that is people get a little free-spirited and we'll get some jerk in there with a turbo'ed unit on street tires that annihilates people in the straights.
Oh, forgot another GT2 car: Viper Competition Coupe.
I'll have to do some testing with it to see if it needs upgrades in order to stay competitive. I'll come out with a complete list of allowable upgrades to the GT2 cars so we can keep it competitive. I can tell you right now that the Panoz GTLM will always stay stock. That car is a threat with a decent driver at the helm.