My c7 z51 made 418whp and 424wtq stock. Its a m7 car too. Had it at the track on a hot and muggy day on stock wheels and tires it went 12.2.
from what he says his 302 boss is 580 to the wheels I haven't seen the dyno sheet. but that's what he said. I know he has cams headers and rebuilt the whole top end of the engine. and has 373 gears in the rear. its a really nice looking boss. I haven't gotten a chance to run him with the shelby I'm sure with his weight advantage his is faster unless he spins more. I've only done intake throttle body and pulley. so I'm close to 700 hp.