My 850TC replica has a race cam, and the exhaust fumes are quite irritating to my nose and throat.
So I have created a way to bring fresh air to my face as I drive. The side window does not really let fresh air in because the airflow hits the windshield and goes outward away from the window area. If you put your hand out as you drive you can feel that there is almost no air flow next to the window but it flows very fast just to the side of the windshield.
This system brings this fast-moving, fresh air to my face as I drive. The aluminum tubing is from a home repair store and the plexiglas air scoop it goes through is from a racing parts supply company. The air scoop alone does not bring any air in for the reasons discussed above..
Even at 30 miles per hour there is excellent flow to my face.