I've seen black zinc-plated rotors advertised that fit the GXP. I don't think I've ever seen a car with these installed, but I believe they would look cool as ****. Would they stay black over time, or will the zinc wear away? If it does, would that be a reliable indicator that the rotor needs to be replaced, or would it just be a surface thing, just as if they were painted, and just as useless?