The Superchips enhance horsepower, torque (the good stuff), and create firmer shifting points to get max performance out of each gear. The chip also turns off the rev-limiter. However, some chips adjust it and basically place it at a different level with the RPM's. The superchip turns it off. You can sit in "PARK" and tach it out at 6,000 RPM's. Without it, only about 3,200 RPM's. I have a Superchip programmed for a JXV3 computer. (This code can be seen on the top of your computer that is mounted in the Firewall under the hood in the engine compartment.) Mine is programmed for 87 Octane with Intake and Exhaust. If you don't have exhaust, it really doesn't matter much with the chip. Though, with it, you can get even more performance out of your Sport Trac! All very good investments! I am selling my chips. I also have a Diablo 3-stage(program) chip. It has 91 and 93 octane programs and also stock. It has a 3 stage switch that mounts in a concealed area in the cab of the ST. These are both for JXV3 computers. The Diablo and Superchip, both, I used for about a week or so. The performance is awesome! I am wanting to get $100 shipped for each of the chips. Drop me an email: [email protected]