Its personal preference, but I try to make the distance to the centre of the screen to your eye, the same for all 3. It tends to give you the same focal plane when you glance to the outer screens IE (checking mirrors or other cars beside you ) thus not requiring your eye to refocus to any large degree.
I tend to think this would assist in reducing eye fatigue in long races where concentration is needed every second.
I know some of the guys I race with are mentally fried at the end of an hour, let alone a two or three hour enduro, which I compete in from time to time. Adding eye strain to that by having to re-focus all the time could see you mentally fatigue, and off the track quick smart
Therefore the angle is determined by the distance, the further away the screens are, the flatter the angle to maintain the same viewing distance.
Of course this is all my own opinion, and may have no relivance at all, but test it out for yourself and decide what works best for you. :D
[/img]
pls note that in the above pic the top desk is pushed away from the wheel to get all 3 screens in shot, the keyboead actually sits on the upper desk and the whole thing slides back and is rebated to fit up against my G25 and shifter
this may give you a better idea
[/img]
[/img]