Like most modern cars, your 2005 to 2009 Mustang GT's V8 engine is constantly monitored and controlled by an advanced Powertrain Control Module (PCM). The PCM's stock computer files (tuning) tells your Mustang how to run. While the factory tuning keeps your Pony running reliably and with few problems, you Mustang is capable of much better performance. Our selection of handheld tuners and monitors from SCT Performance, Diablosport, and Superchips all upload new computer files to your Pony's PCM and can get your vastly improved horsepower, torque, fuel mileage, and throttle response without even needing hard parts at all. Tuning your Mustang's PCM may also be required when you throw on powerful Mustang performance parts that change your air/fuel ratio to the point where your stock tuning can't compensate. For those occasions, we here at Stage 3 Motorsports can use our own custom tuning to get you the best performance out of your chosen parts. If you're looking for even more performance, take a look at our 3V Mustang GT performance packages, Mustang Axle back exhaust kits.