We sell brakes and I dont know anything about them Tom, except if they are anything like the OEM metallic brakes that it appears they want to replace, or add to a car, it will be hard to stop until they get hot. No one offered any advice on the RPO 686 metallic brakes when I ordered my 62, I had to find out for myself and blew the first red light I came up to. However they are still on the car and will probably never wear out. Now at around 35,000 miles and 42 years later the brakes are still in nearly like new condition. In competition the results would probably be very good. Otherwise as a street driver I would stay away from them or learn how to stop all over again..