Airflow through a flow bench is not airflow through an engine.
What you think happens in an engine and what you think the air will do are 2 different things. A smaller intake manifold port (within reason) dampens reversion because the smaller port increases the velocity of the charge as it leaves the carb and through the manifold limiting the reversions ability to disrupt flow by continuing higher.
A slightly smaller intake manifold port allows the fuel on the walls to be re-entrained improving the mixture quality and strangely enough so does a smaller carb aka improved homogenization of the intake charge. Again what the flow bench tells you and what the engine sees are 2 different things. If the flow is both ways then the assumptions you make about it being only one way are clearly wrong.
Larry Meaux said that he had a hemi engine on his dyno that had a volumetric efficiency of 140%, only problem was it was losing 20% of that out the exhaust during the overlap period.......What you get and what you use are 2 different things.
Why didn't that streetmaster intake with its tiny port choke that 340 to death? The difference between it and the Airgap is huge yet it wasn't refelcted in the power at 5600 RPM if airflow is all that matters? 10 Hp difference........There's more to this than just raw airflow.