I purchased a 2005 RX330 Thundercloud Edition recently.
It came with map data 4.2.
I purchased the new 11.1 from Lexus and burned a disk with the 4.2 loading.kwi file.
So far is working very well.
Have not been on any road trips yet but system seems to work without a flaw.
Override is still present and operating as it should.:,woohoo:

 

So would the factory 11.1 disc disable the override forever? Or just while this disc is in?

 

yes, the new version will disable the override. that is why some people create a hybrid disk. i tried to create a hybrid disk one time but IIRC i had a problem where it was screwing up my nav screen one time so i put back the original 11.1 version. the hybrid disk worked for the most part but there was one instance where it messed up my screen so i stopped using it.