What's the best product to use when painting them... I tried plastidip... Pealed rather quick...????

 

A surface like that needs to rough. Ideally sand blast. Or a rough / coarse scots bright with lots of elbow grease. A self etching prime, follow the directions. Prep is the key, as you have found out nothing will stick to a smooth surface.

 

ps - amp running boards are already black and are way cool.

 

Thanks a lot I will try this ... Then go buy some new running boards haha

 

Used black ones or the FX4 style pop up on craigslist or even for sale on here.