New sheetmetal from places like NPD, the black finish that it comes in. Is that a powdercoating, or just a gloss black primer? Should that be taken down to metal before my main primer is sprayed? Or just go over it?

It's "E-coat" primer. It's good stuff but you need to scuff it up before priming again.
Roger

Becareful of that "Ecoat" as you NEED to know if it is indeed ecoat. Some places will just spray a cheap lacquer based product on the panel. NOT something you want to base your paint foundation on.

In order to make sure that Ecoat is ecoat take a rag with some solvent lacquer thinner will do nicely. Then wipe it over the panel if you have the primer show up on your rag then you NEED TO REMOVE IT

If its Ecoat then it will pass the slovent test and NOT show nay color on the rag.

If it is Ecoat then dont remove it, its full of zinc and helps protect the metal from rust. All you need to do is da sand that panel with 320/400 and then prime away...Eric

Thanks guys graemlins/thumbsup.gif good tips