Any type of clear coat over flat will raise the shine of the flat. You have to use a "matte" clear to get the semi-flat look. It will never be as flat as the black flat paint when you apply the clear, but it will be more durable. My side covers and tank were sprayed with a flat semi-metallic silver paint. I liked the look, but knew that it wouldn't hold up to the elements and would oxidize easily. So, the sprayer applied a gloss clear and now it is element proof.
Sparty