It's not an update on the 09 or the 11 it's actually the model refresh from the previous version
MU was the update that changed to the boomerang silver panels on the leading edge of the tank compared with the previous version It had slightly more power and some other tweaks and came in during '08 (my '08 was an MU)
TU came in with the new twin cam design, the exhaust valve added and again had slightly more power. I believe it came in during 10.
I wonder what the Wasser boxer designation will be?