Rat Bastid.
None of the you tube videos in this thread support your contention that the opening in the intake man where it meets the head should be bigger & that it helps power because a smaller opening kills power, posts 28,40, 89. You mention fluid dynamics.
Water is a fluid. To duplicate the above scenario, where the port in the head is smaller & overhangs, get a garden hose & aim it at the corner of your house. See if you get smooth flow...