The Ford Mustang Shelby GT500 is the most powerful factory Mustang ever, but that wasn't enough for Texas-based tuner Hennessey Performance.

Hennessey's Venom 1200 Mustang GT500 extracts 1,204 hp and 902 lb-ft of torque from Ford's 5.2-liter supercharged V-8, up from the stock 760 hp and 652 lb-ft of torque.

Ford Mustang Shelby GT500 Hennessey Venom 1200

Ford Mustang Shelby GT500 Hennessey Venom 1200

That power boost comes courtesy of a new 3.8-liter supercharger (replacing the stock 2.6-liter unit), a higher-flow induction setup, and higher-flow fuel injectors fed by billet fuel lines. The Venom 1200 also needs E85 fuel to make full power. A heavy-duty supercharger belt, a heavy-duty tensioner, and an air/oil separation system help handle the demands of this more adventurous tune.

Power is still sent to the rear wheels through a 7-speed dual-clutch transmission, which gets Hennessey-specific calibration.

Ford Mustang Shelby GT500 Hennessey Venom 1200

Ford Mustang Shelby GT500 Hennessey Venom 1200

Production is limited to 66 units, and the upgrade is priced at $59,950 on top of the price of a donor vehicle. The Mustang loses the Shelby GT500 model for the 2023 model year, the last for the current-generation Mustang, so finding one might be difficult at this point. For an extra $4,950, Hennessey will apply a livery inspired by the 1966 24 Hours of Daytona-winning Ford GT40 Mark II (shown in the accompanying photos).

Hennessey isn't the only tuner offering a four-digit power upgrade for the GT500. Shelby American unveiled its own GT500 Code Red upgrade in August, boasting 1,300 hp and 1,000 lb-ft of torque on E85, or 1,000 hp and 780 lb-ft of torque on regular pump gas, plus a wide-body kit and carbon-fiber bits. But Shelby's version costs $209,995—excluding the cost of the donor GT500. Shelby only plans to build 30 cars, so it will at least be rarer than Hennessey's GT500 upgrade.