I agree that it was probably just a decorative treatment but it probably had some effect on the surface of the aluminum. There is a problem with the kit in that the cowling has no panel lines when in fact there were at least two side panels, a top, and a bottom. I scribed mine and used them as guides when I applied the Bare-Metal foil. Photos on the internet show the locations as do the decals with the kit.
I suspect they actual panels were formed by rolling more than by hammering over a wood buck. The real thing looked pretty slick to me. I wonder if they used a jig or if it was free-hand. It looks pretty exact. Anyone know?
MB