I just watched GM Authority Daily Digest showing a GTO blowing away a ZL-1 Camaro. Just a fixed match up, the GTO would require a diet and modifications to do this.
The "cheater, legal" 500"+ engine stuff is a different race series called F.A.S.T. - Factory Appearing, Stock Tire.I had no idea this was the same series covered in Hemings muscle car. I followed articles in you tube that has Camaro’s /Corvettes running in the high 9’s and 10’s but these are “cheater, legal” engines according to the rules. They run turned down stock tires to increase footprint.
I would expect the GM ”showdown” to be “stock” as the clip implies. But as you guys pointed out this is not the case,
From a bit more investigation these “stockers” have 500 plus cubic inch engines. Anything that is not visible is allowed to be modified. Appearance as original seems to be the only requirement.