Results: Porterfield R4S brake pads!!!
I installed the R4S brake pads with brand new Brembo OEM rotors on my ML55 last week and I have been runing with them all weekend. I took a trip from Miami to Daytona and back. So far the pads have done their duty. They have far less dust then the OEM pads, the braking effort is better then stock only when after the brakes have been heated up a bit. You actually need more effort to stop the car when the brakes are still cold. They make a slight hint of squeek when they are still cold only right before you stop. All and all, so far I am really satisfied with them.