Roush 2015-2017 Ford Mustang Phase 1-to-Phase 2 727HP Supercharger Upgrade KitThe ROUSH Phase 2 supercharger upgrade kit builds on the outstanding performance of our Phase 1 supercharger system by adding proven core components and careful calibration, for an additional 57 horsepower and 65 lb ft of torque over our 670 hp 545 lb ft system (PN 421823). The result is an outstanding 727 hp 610 lb ft of torque while retaining the daily confidence you expect from the engineering of ROUSH Performance. ROUSH engineers spend hundreds of