Stu Ritter, retired MB supertech, wrote an article in the MBCA Star magazine about his 400e brakes. With upgraded stainless steel brake lines, he reports that his 400e stops so hard that the tires will rotate around the wheel. Further braking improvements will just rotate the tire on the rim faster. (I can't imagine that this is good for the wheel balance weights.) He said that his car stops like a Formula 1 racer now. The 500e brakes, (plus stainless lines), would seem to be excessive.