Originally Posted by Mike Benvo
You can update it to whatever OEM software you want without fear of warranty rejection.
However, you might cause issues if you update the DME to the newest version and fail to update other control units in the car.
In fact, this could potentially halt the dealer systems and could potentially mark your DME is failed when hooked up to BMW diagnostics equipment. This is because the ISTA/P integration level is different across modules in the car.
If you are going to perform an update to the DME, make sure you flash the rest of the car to the corresponding software level as well.
Is it still as complicated as how PG outlined it? Need a special cable, super special battery charger, etc. I'm referring to all modules, not just DME.