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There's horsepower, and then there's dyno-tested, can't-lie-to-your-friends horsepower. If you want to know how much power a car really makes, you've got to strap it to a dyno and spin it to redline. The guys over at 5.0 Mustang & Super Fords are always eager to find the true horsepower of a car, and so when they took delivery of a GT500KR to review they headed straight to the dyno to see how much power the supercharged V8 is putting out. What they found was somewhat surprising -- the KR produced 509 horsepower and 467.7 lb.-ft. torque to the wheels. Adjusting for an estimated driveline loss of 15 percent, the actual output at the flywheel is 589.82 hp and 550.24 lb-ft torque -- nearly 50 more horsepower and 40 more lb-ft than Ford is claiming. Take that Z06!

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[Source: 5.0 Mustang & Super Fords]