670 HP Roush Mustang Is The Best Kind Of Dark Horse

Roush Performance is a name singularly associated with modifying your ride for maximum performance. Their 670 horsepower "RS3" or "Roush Stage 3" high-performance mods to this 2015 Mustang make for an absolutely blistering ride on an already wild pony, putting it just shy of the Shelby in terms of the perfect synergy between power, performance, and style.