Painting Boxster calipers

[Micwalser]

I have a 2004 Boxster and I'm thinking of painting the calipers. I notice the calipers seem to have smooth portions that seem to be made of something other than metal (smooth portion of the caliper where the Porsche name appears). I'm concerned the paint won't adhere properly. I was thinking of using G2 caliper paint. Has anyone else painted their Boxster calipers? Any problems? Anyone know if Porsche calipers are constructed of some other material than metal?

Thanks