A tune on this motor is a good idea as the factory tune tends to pull timing. Even GM recommends tuning of the motor.
The baseline numbers are very strong at 549 rear wheel horsepower and 586 lb-ft of rear wheel torque. After the dyno tune by Vengeance Racing horsepower climbs to 593 to the wheels for a gain of 44 horses. The peak torque figure to 601 lb-ft at the rear wheels.
The majority of the gains come due to increased torque toward redline. Owners will see a definite benefit on the top end where the LT4 motor really needs it.