I think the hub is basically the same as if you would turn the rotors off a stock rotor/hub. The addition of the floating rotor onto the hub widens the track width. So the aluminum hubs have the outer face of the hub in the same place as stock, so the thickness of the floating rotor is added.
I know that with DoctorDiff’s 13” cobra kit about 3/16” is added to the 73+ factory track width. Which is about the thickness of the rotors at the hub face.
