The 2005-2009 Whipple/FRPP SC kits have now been upgraded to 550HP (using a conservative 12% powertrain loss). The difference is the new Generation 2 Whipple supercharger which has increased efficiency and increased flow, equaling slightly more boost (still setup for 91 octane) as well as a later generation PCM flash tool and upgraded tune. This makes the Whipple/FRPP SC kit the most powerful, pump gas, 50-state emissions legal supercharger system today.