Read and study this thread carefully
viewtopic.php?f=42&t=13063Even I managed to convert my ms41.0 to 41.2 without any issues, nor did I have any prior experience. Only by reading the threads as indicated I was able to do it. You need to turn off some dtcs..
in the end i went back to ms41.0 because there is no performance to be gained from switching to ms41.2 for me at least...