Wiper Issues? Pls help in advice

[jumpman]

Hope some sifu's can shed some light to this small problem I have with my wiper. When it's on speed 3/highest speed it tends to rub against the windshield rubber but that isn't the case with the slower speeds. also, there is juddering on the driver's side wiper. What seems to be the problem here ?Another question I'd like to clarify. Which is the proper position of the wipers ? There is a straight wiper arm and also the curved wiper arm right ? The straight one is for the passenger side while the curved one is for the driver side...this is my current setup..can anyone clarify this ?Note that I am using 18" wipers and I understand that a standard E30 is using 20" for both sides, will there be an issue for the downsize?Would appreciate any comments that will shed some light on this issue =)Thanks!