Hennessey last summer announced a performance upgrade for the 2024 Ford Mustang Dark Horse, which promised to lift output from the stock 500-hp rating to a supercar-worthy 850 hp.

Ford hadn’t delivered any examples of the Dark Horse at the time, and as a result Hennessey didn’t have any performance numbers to publish.

Fast forward to today and production of Hennessey’s upgrade for the Dark Horse, known as the H850 upgrade, is currently underway, and the Texan tuner has confirmed the all-important numbers.

Peak output comes in at 850 hp and 650 lb-ft of torque, courtesy of a supercharger for the stock 5.0-liter V-8. Other key modifications include a high-flow intake, upgraded fuel injectors, and a new fuel pump. Hennessey also adds its own engine management software to ensure everything runs smoothly.

Drive is to the rear wheels only, via a 6-speed manual or 10-speed automatic. The automatic is the quicker option here, and will see the Hennessey-tuned Dark Horse sprint to 60 mph from rest in just 3.2 seconds, and pass the quarter-mile in 10.9 seconds at 133 mph. The stock figures are 3.7 seconds for the 0-60 mph run and 12 seconds at 118 mph for the quarter-mile.

Hennessey announced a price tag of $49,950 when first announcing the H850 upgrade a year ago. That price doesn’t include the cost of the donor Dark Horse which starts at roughly $60,000. It does, however, include a 3-year, 36,000-mile limited warranty.

Hennessey also offers a range of additional upgrades as options, including an aerodynamic package consisting of a front splitter, side skirts, and a rear spoiler all made from carbon fiber. A set of forged wheels and Hennessey’s Heritage-style graphics are also available.

For buyers looking to save some coin, Ford offers an 810-hp supercharger upgrade for the Mustang GT and Mustang Dark Horse, which includes everything apart from installation for just $9,995. Famous Ohio Ford dealership Lebanon Ford also recently announced a turnkey 810-hp Mustang costing $49,995.