Looks like there is going to be 3 different brake setups for the 2015 Mustang.
The upgrade kit for the EcoBoost models steps up to four-piston calipers and 352mm rotors on the front, single-piston calipers and 330mm rotors on the back, a 3.55:1 final drive ratio and unique 19-inch black wheels.
Best braking performance comes with the GT performance pack. It borrows from the 2014 Shelby GT500. Six-piston Brembo calipers grab onto 380mm rotors in the front, while power comes from a Torsen differential with a 3.73:1 final drive ratio.
The base braking system is 4-wheel disc, with vented with Anti-Lock Braking System (ABS).The drive ratio would be 3.15:1 limited slip.