Don't know of they do it anymore, but the F.A.S.T series. Factory Appearing Stock Tire. It's like F1 for muscle car guys! Haha! They spend crazy money on little motor tweaks, suspension, and skill! But look stock, and run in the 10s!
Now, a guy with a 71' 429 SCJ Mustang in the 9.80s. Looks factory! Crazy!
I met that guy at the Mopar Nationals a few years ago. He did get that car into the 9s and at that time held the record for that class. He sold the car and built another one. It was at the Nats that year but I don't remember what his times were. I can tell you though, they were very impressive considering what he has to work with.
F.A.S.T. is very different from pure stock. Pure stock does allow a few things like radial street tires, a 2.5" mandrel bent exhaust, and I think 1.5 points more compression but they still have to run 93 pump gas. The cam has to be pretty accurate but only when measured at 0.050 lift. Guys running Mopars can really take advantage of super steep ramps with the .904 lifter but even then, there's only so much you can do with stock parts. The internals are pretty regulated.
Iirc, Bob Karakashian volunteered his A12 Roadrunner to tech inspection after it ran high 11s in a pure stock muscle car drag event. I think his hemi cuda has been 12 flat.