I'm interested in the thought process behind allowing both unibody cars and tube frame chassis in the Rolex GT class. It's strange watching Porsche cup cars race against tube frame cars that aren't much different from each other besides their skin.
For instance, last year, Automatic Racing ran what was supposedly a "BMW M6". While it did have super sweet carbon fiber body work, it had virtually nothing in common with an "M6". It was a tube frame chassis that, sans bodywork, looked suspiciously similar to the deskinned "Pontiac GTO" also racing. And the "M6" wasn't running an "M6" motor either. Given the V8 ceiling, they had to run what was basically an e39 M5 V8. That same rule keeps the Viper out of the GT game. In fact, I know folks have lobbied Grand Am to let them run a Viper, but it would have to have a V8 as well.
It would be more enjoyable, IMO, if they did not allow tube frame cars in GT. Let Vipers, Corvettes, Porsches, Ferraris, BMW's, etc mix it up. I'm all for leveling the field, but don't do it through the use of silhouette racers. The prototype category already does that. Let GT be actual production cars, even if they start as bodies-in-white from the factory.