Hello Larry,
That's a good question. We have considered doing GNS/GTN software updates at Oshkosh, but to be done right, the installer should always capture/document all the settings before performing a software update, and verify that they are still correct after the update, and this is pretty time consuming.
Additionally, there are sometimes updates required for GTN attached devices like audio panels, and to update one and not the other might leave the equipment in an unusable condition for the owner's trip home.
Transponders are quite a bit simpler, and as you probably know, we have been updating those at SNF and OSH for several years.
Hopefully you know a good Garmin dealer who can help you out with the software update for your 430W.
Thanks,
Steve