I got my Por15 today. All instructions I've seen say that it works best over rust, but I can't bring myself to do it. Do you guys use the metal prep? I'm sandblasting the parts (some have been blasted and primed,so I'm blasting again)will that be good enough? Will it flow out and look ok in my engine compartment if I brush it on? Is there any way to coat the inside of the cowl? Thanks for any adise.