Hennessey has come out with a supercharger upgrade for the C8 Chevrolet Corvette Stingray that sees the mid-engine marvel’s performance lifted to supercar levels. The Texan tuner on Tuesday announced the H700 upgrade that dials output from the Stingray’s 6.2-liter V-8 to 708 hp and 638 lb-ft of torque. That’s up on the peak 495 hp and 470 lb-ft of…