http://www.raylarengineering.com/vort...
The all new 2.9L Whipple twin screw supercharger kit for 8.1L Vortec engines makes 590hp / 695ftlbs on 8.5lbs of boost with stock cylinder heads! Up to 12lbs of boost is possible with this supercharger kit.
*Forged engine internals / rotating assembly are required for reliable operation with our supercharger kits.