The ponycar fanboys at 5.0 Mustangs and Super Fords took a Shelby GT500KR press car, strapped it down on a Dynapack chassis dyno, hit the gas and recorded a monster 509 HP and 467.7 lb-ft of torque. When you factor in driveline losses, that means the King of the Road is putting out 590 HP and 550 lb-ft. That's…