I have to abraisive blast and paint several Items yet for my 50 studie champion. including heat ducts , blower motors , fan blade and several floor pannel hole access covers. I have purhased por 15 and the por15 top coat for this , I have used this on the underside of the hood and trunck lid and I don’t realy like the brush marks it left . Does any one have experience with spraying por15? And if so what should I thin it with and how much?