Rex,
Stan and I have had discussions about Air Scoops vs. Air Ducts. We both run Street Roadsters and the rules regarding Hood Scoops have changed in 2009 to limit the front of the Scoop to the front hood line. The rule was intended for other body types but we got swept up by it for this year at least.
With a non-taped Air Duct such as Stan runs, the expansion of the cross section is internal to the Duct. He also said that this should be just inside the inlet (opening quickly). Should that divergence be a certain angle in relation to the distance from the inlet to the carb, say 45 degrees, or 90 degrees to airflow at the inlet face, or some other angle?
I understand that in addition to pressure recovery the goal is also to reduce turbulance in the plenum.
Tom