E46 M3 Rear Porsche Brembo BracketsUpgrade your single piston rear calipers to a 4 piston caliper from the Porsche 996 or Boxster S. CNC Machined Brackets are designed to fit a Porsche 996 Brembo rear caliper to the E46 M3 rear mounts. The rotor used is your standard E46 M3 328x20mm rear rotor. You may use the standard rear rotors or two piece rear floating motorsport rotors (they are the same dimensions). Brackets are made from high strength steel and cad plated for corrosion