The GT500 with it's forged 5.4 supercharged engine and Tremec 6 speed is the best foundation for huge horsepower street car. We have many customers with 700-800hp from a Whipple Supercharger on the stock engine. Even a Steeda cold air intake, pulley and tune will make over 600hp. The suspension is key to put the power down so add some Steeda billet control arms, springs and Tokico D-spec adjustable shocks with some big sticky tires in the back.