The ROUSH Performance Phase 1 to Phase 3 Upgrade kit improves the power gains of your 5.0L Mustang Phase 1 ROUSH supercharger to 675 HP and 585 ft-lbs of concrete-smashing torque. That's an increase of 100 HP and 80 lb-ft of torque -- more power to dominate the streets!This upgrade kit offers better performance and added protection to meet the high demands of this much horsepower. To meet the increased fuel demands the ROUSH Fuel Pump Voltage Regulator and Plug-n-Play wiring harness offers are added to help regulate fuel pressure. The ROUSH Plug-n-Play wiring harness allows for easy installation or removal if the kit ever needs to be removed. No cutting or splicing of factory wiring and harnesses required.