Even if the air intake was directly in the front, the ram effect would be insignificant. Given that a radiator and a grill is upstream, there is no ram effect due to forward speed. The air cleaner restriction due to the flow resistance of the snorkel is the dominant factor. At low engine speeds is of little significance, but at higher engine speeds, it is. Both my 68s have a second hole in the air cleaner (one has a snorkel, the other none doesn't) and in both cars the improvement is small but noticeable (only at WOT). There may be some more improvement with an open air cleaner, but I was concerned about the noise at part throttle. If you do install a "forced" intake from outside the car to the snorkel via a wide hose, the benefit is from the lower temperature rather than ram effect. At higher speeds where the underhood flow keeps lower temperature, the effect will diminish. D^2 Quoting johan C wildhagen <johancwildhagen@xxxxxxxxxxx>: > > 1. Am I correct in thinking that open "pie plate" type air filter > covers > are an advantage with low speed stop and go city driving, as factory > (413) > "snorkel" types are for highway and higher sustained speeds per the > forced > air entering thru the grill in to the snorkel? > >