I believe the main idea with the air box was to house/enclose the different length
velocity stacks in a filtered chamber. The key to the design is to equalize the total
lengths of the intake from the valve seat to the end of the velocity stack, the only
variable is the location of the throttle butterfly within the total length. Notice the
longest stacks are on the shortest ports and vice versa. When you go to pods, equal
length stacks or carbs that don't use the stock airbox, you lose the intended equal
length intake tract and disrupt the balanced airflow to each cylinder.
Mr. Irimajiri stated in one of the design reviews that it was the intention to equalize
port length variation caused by the necessity to pull the carbs closer together and
angle them in the V formation, all in the name of rider comfort/knee position.
Irimajiri wanted straight ports like the RC166 but was overruled by the styling engineers
and thus the compromise of intake tract design.
Note if you use carbs other than the stock CVs, the straight across bank (non V style) you
are much closer to the original equalized total port length idea as varied intake manifolds
take the place of the different stock velocity stacks in the airbox.
Well, I had just written something about header tube lengths and how they relate to IN. port
lengths but when I hit submit my text vanished. I'll try again later.