The more coat you put on the better the shine will be. Of course, you can't just keep adding coats, even if very thin ones, so I'd suggest you put a number (5 or 6)of thin coats with an airbrush, then use turtle wax or something similar to get the shine you want. The more Future you have, the less likely you are to get through to the paint, or worse the plastic (just happened to me with my Porsche 928...!)