Wouldn't the length of the air passage through the adapter be one the the major adapter concerns, if it was longer and had gradual shape changes instead of sharp turns that would create a negative turbulence the passage shape could be changed with little or no harmful effects I would think. Once the charge is compressed and is away from the compressor I would think that a smooth shape with no sharp changes would be the most critical thing not shape.
I have never messed with them but why not? Why wont the charge flowing through the adapter stay charged as long as the compressor is turning fast enough to supply more air than the cylinders can use, same as a roots blower. I was under the impression that screw type and axial flow compressors did the same thing a roots type does but was more efficient and kept the charge cooler. Not disagreeing, trying to learn been considering adding one to my 300 inch Ford.