The idea from the factory is that the manifolds were never painted. They were bolted to the motor as bare cast parts, then the entire engine assembly was painted. Factory manifolds could have come away with either just a little over spray or completely painted, it depends how the painter felt that day. Nobody can really say how much paint was applied for sure because it burnt off in a matter of minutes of the engine running, leaving only engine colour on the cold spots of the manifolds such as the mounting nuts etc...
Mine have been ceramic coated first, so the orange will burn off but the grey colour will not, they will stay grey forever.