Many moons ago a study of wind flow was conducted and discussed on emog, I can't recall who carried out the study using streamers. The study concluded that the wind deflectors did very little deflecting. Due to the aerodynamics of the cockpit and the windscreen air is drawn into the back of the cockpit and from the sides. The deflectors simply push a small amount of air further out before it comes back in and increases the air flow between the deflector and the windscreen pillar. Sidescreens were far better, that's what they are there for, although of course the wind still comes into the cockpit from behind. As with all things Morgan it's a personal choice.
