the bellypan simply relates to the comment about the hood flexing, has little or nothing to do with noise or the visor, and I doubt it'd reduce wind resistance much .... not likely there's much of anything you could do to cut through the wind easier, short of a major redesign of the entire front end, including the windshield shape and the slight original brow above it
I believe GM made the change in the hood shape in 58 as the cheap/easy fix to the hood action in the 55-57, the 58 and 9 don't seen to do that at all
Bill
