I don't belive you can do anything with the engine without voiding a warrenty. Maybe you can buy wheels, lowering springs, and a body kit. If it was me, I'd call the dealership or Ford and ask.
My first car was a 67 Mustang Coupe, 2nd one was a 67 Cougar XR-7, 3rd one was a 66 Mustang Coupe. Why did I get rid of these cars for ? I know why, because I'm stupid, stupid, stupid.
My next Ford.....