Actually with just a tune and set of headers the Z06 would be putting more than 480hp to the ground - and I am willing to bet this "race" would have had a diff. outcome had the Z06 driver actually pushed his car.
Slow shifts and starting at low revs really took its toll.
The M6, like most Eurocars, comes with the engine tuned to its upper performance envelope - The Viper, Vette and Ford GT come from the factory with engines relatively "under tuned" and are only at the lower end of their performance envelope.
