I've got the Aprilia mirrors (on extenders) on my K4 Strom and I much prefer them to the OEM version.
However .... I get a slight vibration on the LHS mirror, which makes the cars behind look very slightly blurred at 40mph and above. I couldn't read a number plate in the LHS mirror. No problem with the RHS mirror, where everything is sharply in focus.
Does anyone else see this problem? I have checked and rechecked all the mountings and everything seems to be the same on both the LHS and RHS. Both bar ends are present and correct. I wonder if I am just gripping the throttle side more tightly than the clutch side.