Good discussion guys, and most of you make great points. Adam didn't just run one modded C6 Z06 though he ran two, as well as other cars that probably should have pulled him. So Adam's car is performing better than I thought for sure. Adam also ran even with Ryan@shift-s3ctor's Cammed C6 Z06, which pulled the VT650 Arkym car at the last airstrip event 2+ cars (vid below). So it appears his car is just as fast, probably faster. Also Ryan's Z06 in the below vid, pulled a intake / tune C6 Z06 last weeked by 3 cars, so it's running right where it should be.
As far as Robert's Z06, I do think the passenger slowed him down probably a car or so, and that he probably could have shifted a little faster, but he still did well and was creeping ahead at the end. His Z06 did not spin the tires, it was a clean run, he had full traction. Either way, Adam's car is moving well.