If the stripped and track-focused Camaro Z/28 is something like Chevy's version of the Porsche GT3, Hennessey just made Chevy's GT2 for them.
It's a 636 horsepower Z/28, the first one with Hennessey's HPE600 kit. It appears to be a beast.
The car came around because one Austinite got himself a regular Z/28 and found that the "505-horsepower, 7-liter LS7 engine wasn't quite enough," as John Hennessey recounts. Hennessey agreed with the guy, and gave the car the guts to match the forced-induction Camaros of the world.
I would say that this kind of mindset is beyond my comprehension, but I can actually sympathize. Once you try a car with a lot of power, all you want is more.