Quick view Roush ROUSH 2015-2017 Ford Mustang Phase 1-to-Phase 2 727HP Supercharger Upgrade Kit - 421994 Compare $1,299.99 The ROUSH Phase 2 supercharger upgrade kit builds on the outstanding performance of our 2015-2017 Phase 1 supercharger system by adding proven core components and careful calibration, for an additional 57 horsepower and 65 lb-ft of torque. The result is... Add to Cart Add to Cart