it depends what kind of paint system you are using, if its a bc/cc then yes you are suposed to clearcoat, if its a single stage then no clearcoat. im not really sure what you are useing or are planning to use so its kinda hard to answer
I've used Dupont Chromabase and it's not good to load up the clearcoat. I'm not sure what happens when you use too much, but just two wet coats is unbelievably shiny.