Around this time last year I seem to recall, there was an autospies
article about the retrofit kits being available soon after, and included
all the BMW parts for the various kits.  The kit included one for the
convertible.  I contacted the manager of my dealership and he researched
the part I quoted but said it didn't exist, nor could his sources tell
him when the convertible kit would be available, although the other kits
(for the coupe, etc.) did become available in the fall sometime.  Since
then, I've been contacting him ever month, and also writing BMW customer
care every month, asking about status - kit still not available and BMW
customer care says they are still working on it - having microphony
problems I gather (not surprised - this is an open-top car!)  I'm
hopeful that the ingenious engineers at BMW can solve this one, and
soon.

Jon