[HardcoreZ28]

You can sandblast them but I would suggest a few good coats of primer to even the surface out after before paint. And be careful if you use sand.....too much heat could warp the covers and cause leaks. Also be sure to wash them very very well to get all the sand out, especially if they are baffled.

An alternative to painting them would be powedercoat as well....for a much more durable finish.