I can't recall if I dreamed it, or we did it by email, but I thought JFFR took measurements that showed his filter box became pressurrized. the info included the "thickness" of his scoops and "speed of air" in his ductwork for full throttled conditions. If I recall correctly, full throttled/redline caused the air entering the scoops to be about 40mph. I can't recall the percent of the scoop thickness that was providing ram industion.
an electronic manometer measured pressure in the filter box wrt the pressure over the engine
found this graph in the bottom of the trash can