[Aussie Mike]

Air flow wasn't a problem with the Can Am cars with their trumpets out in the breeze. From what I've read it was just for improved torque spread with the Crower mechanical injection setups.

It may be a different situation with webbers installed under a bonnet. Carbs rely on airflow through a venturi to pull the fuel vapour through into the airstream. Restricting that airflow could have a real impact on metering.

These mechanical injection setups run individual jets for each cylinder to trim them and the crank driven fuel pump combined with a valve tied to the throttle linkage to meter the flow of fuel to each cylinder. They are pretty agricultural and just supply X amount of fuel for a particular RPM and throttle position.

Cheers