The caliper we are using in our Essex Designed WRX Competition BBK is the AP Racing CP8350. This caliper was designed to be ultra lightweight, stiff, and durable under all track conditions. The finish we chose is a hard anodizing, as it is the business under track conditions.
When raw aluminum reacts with the oxygen in the air, a hard surface film develops on aluminum which prevents further degradation. The process is called oxidation, and you can think of it like rust. The anodizing process leverages this natural phenomenon, and takes it a step further to produce an extremely hard protective layer of aluminum oxide on the aluminum. It does so by running an electrical current through an acid bath, and dying it to the desired color. If you want to know more, Google it.
The result is a finish that is far more appropriate for racetrack use. Anodizing creates a uniform surface that is much more abrasion resistant than most paints or powder coats. That means if you ding an anodized caliper with a box wrench when bleeding it, a big chunk of the finish isnt going to chip off into your hand. While anodized calipers will still exhibit color shift, it will take a lot more heat to get them to change, and they wont change as dramatically.
Please do keep in mind however, that every yellow AP logo is hand painted on the caliper. It will degrade over time, particularly if you slop brake fluid all over it. Our customers asked us for something with a little visual punch and some brand recognition, so we had to give them this token. Also keep in mind that an anodized finish is not designed to be driven through road salt.
The entire brake kit weighs 12.2 lbs which is exact 50% lighter over stock brakes !