Performance tuning is more difficult vehicles were the factory computer does not have a chip that can be easily replaced. To solve the problem JET developed a plug in module that attaches to the vehicle computer externally that can add up to 30 horsepower. The JET Module optimizes the ignition spark advance, air to fuel ratios and transmission shifting for the ultimate in power and mileage gains. 06-08 Commander;3.7L 6 cylinder engine;Must use 180 thermostat and premium fuel;Legal in California only for racing vehicles which may never be used upon? a highway