The 390hp supercharger factory Cobra ran pretty good out of the factory. The guys at ProCharger took it one step further and made huge horsepower gains by removing the stock roots type blower and strapped a ProCharger on and the results we're unbelievable. The power totals were in the 500 plus range at the rear tire just to start and have seen numbers over 700+ on a stock shortblock. If you are serious about going fast with your Cobra the only answer is ProCharger.