99-01 mustang 4.6L GT&Cobra Looking for a fast and easy way to add horsepower? These Power Programmer III units are as easy to use as pushing a button, and require no tools. They plug into your vehicle's sub-dash diagnostic port, and reprogram your computer with true performance curves for fuel and spark. Hypertech's programs will give you more performance throughout the entire rpm range, not just in the top end, like other brands.