Here's why:
* The Evo's inherent advantages: The Evo, even stock, is known for its all-wheel drive (AWD), giving it superior traction, especially in launches and poor weather conditions. The Mustang GT is rear-wheel drive (RWD), making it prone to wheelspin. The Evo's lower center of gravity also helps with handling and cornering.
* Aftermarket parts: The significant variable is the *type and quality* of aftermarket parts on the Evo. Serious upgrades to the engine, turbocharger, exhaust, and other systems could significantly boost its horsepower and torque well beyond the Mustang's capabilities.
* Mustang's potential: While a stock 2001 Mustang GT might be slower overall, a well-maintained and driven example could still put up a decent fight, especially in a straight line, depending on the Evo's modifications. Modifications to the Mustang could also greatly change the outcome.
In conclusion: Without knowing the specifics of the Evo's modifications, it's impossible to say definitively. A heavily modified Evo would almost certainly win, but a mildly modified one might only have a slight edge, or even lose depending on the driver and track conditions.