Not sure how hot the cans get... but your best bet if you wanna just go rattle can is engine paint.
If you really want to do it right, have them ceramic coated. Gonna cost a bit more though.
I had my pipes ceramic coated by Jet-Hot. The coating has long since been flaking near the exhaust ports. When I get around to it I'm going to pull the system, remove the old coating, and ratlle can the whole shooting match with matte red VHT.