Couple guys here who have 1968 Hemi a-body type scoops on their race cars have made some air relief cuts or holes drilled in the back side. Maybe too much air coming in at speed messes up the carburetor signal?

My brother put an air pan on one of his cars years ago as it was burbling and not running totally smooth at the top end. It went slightly faster afterwards, but that may have been due to it being able to run clean all the way thru the quarter vs the pan being a speed adder all by itself.