There are some here who did upgrade their A4 B5 from a Symphony I to RNS-E. There are also some with an older A6 C5 who did the upgrade.
Besides the faceplate modifications you will need to deal with more electrical issues the older your car is. In general you should be able to install the RNS-E if your car has a digital clock in the instrument cluster (MY 2001 and newer, some models MY 2002 and newer).
Search for B5 or 2001 here in this forum and you will find several storues from people who have upgraded from a Symphony I to the RNS-E.
Good luck...
Besides the faceplate modifications you will need to deal with more electrical issues the older your car is. In general you should be able to install the RNS-E if your car has a digital clock in the instrument cluster (MY 2001 and newer, some models MY 2002 and newer).
Search for B5 or 2001 here in this forum and you will find several storues from people who have upgraded from a Symphony I to the RNS-E.
Good luck...