As the earlier post wasn’t clear enough about the air assist mod, I made a small schematic to show it better:
The magenta bits were removed so the (green) sleeve and nozzle would make the lens sit exactly as it was, no changes whatsoever to focal length or possible beam interference, altough I really would like tho taper the inside end of the nozzle a bit, because reasons. However, having just installed a very expensive and fancy lens, I think I will wait until it becomes damaged or needs cleaning.
As for having the air stream twirl, that could probably help , but I suspect it would require the aforementioned tapering of the inside, to avoid sudden vector changes. However it would also mean making a new nozzle with an offset air inlet, and I’m not in the mood to do that.