The XX2-Charger delivers 15psi of boost pressure at 8,500rpm producing arm wrenching acceleration and increased top speed. High-performance billet impeller & 4MM spacer increase horsepower through superior impeller blade design and larger interior housing volume. Lightweight billet impeller features a sophisticated blade design that is precision balanced to deliver smooth operation. Spacer & impeller install quickly and easily onto stock supercharger base plate. IJSBA Limited Class legal. Requires RIVA/MaptunerX & VT1100 Injector Kit or RIVA/Vi-PEC Pro-Series ECU, RIVA Pro-Series Fuel Injectors (100lb) & RIVA Fuel Pressure Regulator Kit for correct calibration. Includes detailed installation instructions.