I had my S3 fronts shot blasted and powder coated and I have a set of vRS/GTi rear calipers with DaveB receiving the same treatment. I did however paint the calipers on swmbo's Golf with black smoothrite, and they are fine. My advice would be to get a tin of red hammerite, wire brush the caliper, mask up around the disc, pads etc, then paint it on.
![happy2 :happy2:](https://www.mk5golfgti.co.uk/forum/Smileys/newsmileys/happy2.gif)