I was wondering what the sizes of the front and rear rotors are for a stock Mustang GT. I am looking to replace the front with 14inch rotors and rear with 12in rotors but I don't know how much bigger the rear will be vs. the factory ones. thanks

 

Fronts are 12.4 x 33mm...rear are 11.8" x 19mm.

I don't really see a need to replace the rear especially going up to 12 from 11.8, but if you do consider adding in a proportioning valve. TheS197s I have been running with that have done all four corners (course that is only two - one was NA but modded and the other was S/C) has gobbled up rear pads until the system is proportioned.