Going to paint my GPS calipers red soon and have already had experience of painting calipers on 320. I used VHT paint for calipers from Frosts Auto restorations. 
I applied about five coats after cleaning with drill mounted wire brush and paint prep cloths from halfrauds.
I did detach the caliper from the mounting bracket and then mask around it and spray it on the car.
Two years on it still cleans up well with hose and sponge.
I applied about five coats after cleaning with drill mounted wire brush and paint prep cloths from halfrauds.
I did detach the caliper from the mounting bracket and then mask around it and spray it on the car.