2 Day Brakes Front Performance Cross Drilled and Slotted Brake Rotors 2003-2009 BMW E65 760i & 760Li E66 Our drills are all chamfered and countersunk for a smooth linear contact at the edge of every drill to eliminate brake squeal. Chamfered holes also reduce stress risers which create a longer lifespan for the brake discs. Rounded slots give you maximum slot life so that degassing will become more effective. Depending on application, braking performance typically is improved by about 30% over stock braking systems if used with our recommended brake pads.