And there is a picture on their site indicating its rotation direction and the path of the air down the sides of the rotors as opposed to through the centre.
All the confusion has definately come from people thinking the Mini charger is a Lysholm/Twin-Screw type. While it does have two "thingies" that could be termed screws, they are infact of a very different design and are only mildly helixed rotors to enhance the original Roots design (which dates back to 1860 when patented by Philander and Francis Roots), to the layman they look the same, but work very differently.
Beginning to wonder if I should write an article about superchargers for the MSC magazine! 
