One of those options is the Goliath 650 upgrade that Hennessey Performance announced on Monday. It adds a supercharger to the available 6.2-liter V-8 offered in the trucks, lifting power by 55%. The upgrade delivers a dyno-proven 650 hp, up from the stock 420 hp, according to Hennessey.
The supercharger is a 3.0-liter design, and it's joined by high-flow intake and exhaust systems, an intercooler, a crankcase ventilation system, and Hennessey's own engine management tune. Hennessey said it also swaps out the V-8's standard pushrods for a tougher chromoly set. Drive goes to the wheels via the stock 10-speed automatic transmission and either a part- or full-time four-wheel-drive system.
The power upgrade alone costs $27,950. However, Hennessey also offers an off-road package designed exclusively for the GMC Sierra 1500 AT4. It costs $22,950 and adds items such as a custom steel front bumper with a “GOLIATH” script and additional driving lights, a suspension upgrade that further lifts the ride height, and custom 20-inch wheels with 35-inch off-road tires.
Hennessey has offered previous Goliath upgrades for GM trucks. One of those added an extra axle to the Silverado 1500 to turn it into a true 6x6. Another added a supercharger to the 6.2-liter V-8 to lift power to 705 hp.
Hennessey typically limits the number of builds for each of its upgrades, though the Sealy, Texas-based company hasn't said how many Goliath 650 upgrades will be offered.
Like all of the company's upgrades, a 3-year/36,000-mile limited warranty is included.