Same Size Rotors Front and Rear?

75slant6 said
Hi everyone, I’m installing an HDK suspension in my Duster and am using 13” 99-04 Cobra brakes on the front. So my question is, would it hurt anything to use the 13” ‘15-17 Mustang GT rear brakes on the back? The 2 piston front calipers would obviously be bigger/stronger calipers than the single piston rear calipers, so would that be enough to keep the proper front/rear brake bias or would the added leverage of the larger rear rotors have enough of an impact to mess with the bias?
From my interweb searchings, I’ve found that apparently some new 06-11 police Chargers run same size 12.6” rotors front and rear with the fronts only being thicker. So I’m thinking the 13” front and rear should be fine, I just wanted to hear the opinions of people who probably know more than myself.
Thanks in advance!

Rotor size can be the same front to rear, that isn't where the bias comes from. What you want on a typical RWD car with the engine up front is 2x brake force on the front than on the rear. If you have the same size rotors front and rear then your front calipers need to have twice the piston area as the rears. If you follow that formula then the bias should be close enough that you can dial it in perfectly with an adjustable prop valve. You most likely will want to use the same pad material front and rear and have tires that are roughly the same size front and rear. If you stray from the formula then beware of any panic stops until you get some seat time and figure out what it is going to do when you stomp on it. You don't want to find out the hard way in an emergency.