RB listed the rotors on the front to be 4.5lbs lighter each and the rear rotors to be 6lbs lighter each, compared to stock rotors.
Total Rotor Weight Savings per RB = 21lbs.
After moving the RB rotors and Stock rotors around in the shop, the fronts rotors felt a lot lighter than Stock ones. I have hard time believing there is only a 4.5lb difference between them. The reason I say this, is because the rear ones felt closer to the stock weight, but yet had a bigger weight difference. Don't get me wrong, the rears where def lighter than stock.
Caliper is listed at 4.5lbs and 6lbs with bracket if I'm not mistaken. The brackets where a lot lighter than stock (like a 1.5lbs). Add pads in at roughly 3lbs granted and you are at ~9lbs for a complete assembly.
Total Caliper Assembly Weight Savings = ~10lbs
^In my org post like a d-bag, I forgot to include a pad weight...sorry guys
My Bad.