Hennessey's HPE850 package for the Ford Mustang Shelby GT350 adds a 3.0-liter supercharger to the pony car's 5.2-liter V8 for a claimed output of 858 horsepower (640 kilowatts) and 673 pound-feet (913 Newton-meters) of torque. In this video, the company shows how the tuned vehicle performs against a mostly stock Dodge Charger SRT Hellcat.

To really highlight what the HPE850 package does, Hennessey starts this video by having a stock GT350R race this Charger SRT Hellcat. The Dodge has some very mild tuning, including a different air intake and stickier tires. From a roll, the Charger demolishes the Mustang down the track.

Next, the tuned Ford gets its chance. In addition to the supercharger, the HPE850 package for the GT350 includes a new throttle body, fuel injectors, heat exchanger, and air intake. The company's numbers claim the upgraded vehicle can reach 60 miles per hour (96 kilometers per hour) in 3.3 seconds. It can cover the quarter-mile in 10.8 seconds at 133 mph (214 kph).

The Hennessey salesperson refers to the HPE850 pack as the "Hellcat killer." This video shows why. As soon as the two vehicles begin accelerating, the GT350 leaps into the lead and never gives it up. Plus, the supercharger whine adds a great note to the Mustang's noise.

One thing that makes the HPE850 special is that customers get a supercharged Mustang with a manual gearbox. In comparison, Ford's own Shelby GT500 has 5.2-liter V8 with forced induction makes 760 hp (567 kW) and 625 lb-ft (847 Nm) of torque. Plus, buyers can only the hotter trim from the factory with a seven-speed dual-clutch transmission.

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