I've got series doors on my 90 fitted with Rocky Mountain door tops. As with standard series tops they do flex a bit. (Though not as bad as standard). I've fitted a 1mm x 10mm wide alluminium strip between the join of top and lower half of the doors on the outer edge. This results in the top of the door top, being pushed in against the seal and giving a good fit. Also, if the seal was fully up on the lip under the cab roof, there was a gap. I've fitted an extended lip, 10mm lower, and now have really good fitting door tops. No draughts, no leaks and less wind noise. :D