09 Ford Mustang Roush Stage 3 V8 670hp supercharger stick shift

Roush Performance is an American automotive company primarily involved in the engineering, development and manufacturing of high performance components for street and competitive racing applications. The company's namesake is automotive mogul Jack Roush, who also owns and operates it. It was founded in 1995 by Roush to provide engineering from racing to street cars.

Roush produces aftermarket performance parts for Ford cars and trucks, mainly the Ford Mustang, Ford Focus, and the Ford F-150 light duty pickup. These special model vehicles are sold to the public through select Ford dealerships. In addition to the high performance business, Roush supplies propane conversions kit for the F-150, as well as for school buses.

Modifications to Ford vehicles completed at their Livonia, Michigan factory include upgrades such as suspension, body, interior and engine, depending on the model of Roush vehicle and the options ordered. Perhaps best known of these Roush-modified vehicles is the Ford Mustang, which in 2016 is available in the "RS" (3.7 liter V6, with body kit, stripes, wheels and interior modifications only), "Stage 1" (standard 5.0 liter V8, with body kit, stripes, wheels and interior modifications only), "Stage 2" (standard 5.0 liter V8, with body kit, stripes, wheels, suspension and interior modifications only), and "Stage 3" (body kit, stripes, wheels, suspension, interior, and exhaust modifications, with the addition of an Eaton-supplied 2.3 liter TVS-2300 "roots-style" supercharger). The addition of the supercharger to the Ford-supplied 5.0 liter engine on the Stage 3 version results in a horsepower output of 670. All Roush factory cars are 50 state street legal.