The 99-04 Mustang GT, also called The New Edge Mustang, was a pretty badass upgrade to the SN-95 model. It brought a sharper-edged body style, along with some engine, suspension and performance improvements. Still, you can never have enough power! And if you know us, you know we love upgrading Mustangs — the 99-04 Mustang GT generation is no exception. We've got the Custom Tunes you need to get things rolling. Check out our turbo systems and superchargers too, along with much more. Whether you've got a 1999 Mustang GT, a 2004 Mustang GT or any model in between, Lethal Performance will help you make it the beast we know it can be.