Actual terms vary by lender. I added the Ford/Roush supercharger to the 5.0 for 750 hp and 676 lbs torque. No other car can be upgraded like that. Without the supercharger the car is just ok.
The only other option if you don't want the EcoBoost, GT ... and has two options for the S650 Ford Mustang – the GT and Dark Horse can 'roush' to 740 horsepower and 600 pound-feet of torque ...