for the body guys

brian6pac said
80 is really course, you need to get all the scratches out of the metal first, DP90 epoxy wont shrink like regular primer and your not suppose to sand it. I would do all the metal work first.

80 grit is just fine on bare metal, and gives the primer a good "tooth" especially on a DA sander. Metal doesn't shrink. Paint substrates shrink.