If you're like me, your car/truck isn't the way the manufacturer delivered it, or at least you don't want it to stay that way.  Maybe it's simply larger tires on your truck but now your speedometer is off and you don't like where the shifts are occurring.  Or maybe it's something more like an aftermarket cam, torque converter, turbo or supercharger, or combination.  You're going to need the computer in your vehicle to be "taught" what it needs to know to get the most out of it's modifications, whether changing shifting characteristics, reprogramming due to larger fuel injectors, to name just a couple of a myriad of parameters stored in the vehicle computer so it can operate.  Hoosier Performance Tuner can "teach" your vehicle's computer how to master the changes you have or are planning to make to the vehicle.