What is the factory top speed setting for a 2003 mustang?
There's no single "factory top speed setting" for a 2003 Mustang. The top speed depends entirely on the engine and transmission options of the specific model. Ford didn't electronically limit the top speed of the 2003 Mustangs in the way some manufacturers do today. The actual top speed would be determined by the car's gearing, engine power, and aerodynamic limitations. It would vary significantly between a V6 and a GT model, for example.