Originally Posted by JunkStory
imperial_sloth is 100% correct. The high end Brembo calipers have an anodized surface that is dyed, and doesn't affect heat conduction.
Low end Brembo calipers for upgraded purposes are painted, but even so, because of the sheer size of the calipers compared to stock, the heat capacity is multitudes larger, and there's more surface area... you will still see a huge gain. When you paint your OEM stock calipers, you will only see a loss.
I may track the car after the M3 suspension upgrade is done, so I'll probably just paint the hubs to avoid any potential issues.
If I do paint them, it looks like the winner is Black.
Thanks for all the feedback guys!