Not much to add.... unless someone has the data.
I would be inclined to think the stock screen was designed for the least drag.
The best way to know is by testing in a wind tunnel. Who has access to one of those? Suzuki did when they designed the thing.
The other problem as mentioned is the rider.
The rider is a big part of the air drag factor.
The rider can induce instability depending on his/her profile.
Wind temp, speed, direction, altitude etc. on any given time and place are all things effecting top speed.
A top speed obtained by one rider may or may not be obtainable by another rider on the same Busa.
A definitive answer will be almost impossible to find.
Those speeds are very risky.
Good luck.