With enough mods you can get almost any vehicle to beat almost any other vehicle.
I think that a Mustang can very well beat a Ferrari, yes. And it will be built for less, yes.
But keep in mind you have to plan for a specific style of race. And are you removing any speed limiters? In other words, are you going for top speed, or a race given a specific straight line distance, or specified Grand Prix style course?
It would be a very good race is properly set up… both the course and the cars.
But in my opinion, I would not waste my time with it. They are two totally different types of cars, for different purposes. I would like to see a Ferrari beat me at this race though…..
You must have 4 passengers, and you must also do a weeks worth of grocery shopping. Every passenger must be in their own seat and not on another person. And the groceries can not be held by anyone nor outside the vehicle.
Seriously, like I said, a Mustang is a beast of a different variety. There are differences between a muscle car, a sports car, and an exotic car.