I've tested at the track and on a engine dyno with close doors using a dropped air cleaner base and then with the complete air cleaner and no air cleaner, my 1963 Plymouth Max Wedge steel front in car ran quickest(.020 to .030 up) with the bases only at the track wrench

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)