Dr. Diff 13" vs 12"

It’s not a 12” kit. It’s the 11.75” Mopar rotors from the later b/r bodies with caliper brackets/adaptors for the wilwood 4 piston calipers. So basically you’d have the same size rotors front and rear.

On his website DoctorDiff recommends the 11.7” rear kit for front disks 13” or larger. At the very least I’d say call him and see what he says. They’re his brake kits after all. You could dial the rear brakes back with an adjustable prop valve, but it seems like kind of a waste.

IMO just commit to the 18’s. I have DoctorDiff’s 13” cobra style brake kit on my Duster, it’s a great kit. It replaced a set of 11.75” rotors too, although that was with the stock Mopar calipers. The 13” kit was a noticeable upgrade.