My first bike was a new '69 Yamaha 250 DT-1 and I was 17 or 18 years old during Projekt Ram Air. The engine had Yamaha GYT kit internals with a Schwerma expansion chamber. My buddies and me made a ram air system and could not make it work. The problem was the main jet size. It needed to be larger than it would be without a pressurized air box. The exact size was variable. It would be different when the bike was topped out in third, fourth, or fifth 'cause ram air pressure differed at varying speeds. Also, ram air pressure changed drastically when running against or with the wind. A hole in the piston due to a lean mixture put an end to that project. What I learned was, it is cheapest to figure things out on a single cylinder engine and to stay away from ram air with a carb fed motor. Maybe the folks with EFI have figured out a way to get the mixture correct. It was prehistoric times back then. Carbs was all we had.