>>9325266>Your undercoat is quite important for making your paint stick and it changes the vibrancy of a coat considerably.That's what I thought too when I had no experience with metallics, but that rule is far from absolute.
Pic related is Alclad Hi-speed Silver over bare white plastic, as white as a spoon. Looks just as shiny as over gloss black for all practical purposes. How do I know? I tried both.
Quality of the surface >> color of the surface. Priming for lacquer paints is unnecessary if the surface is already good.