Goes on top of your TMO 2.5 (and small patch) activation:
http://www.subsim.com/radioroom/down...o=file&id=1414
and it's patch:
http://www.subsim.com/radioroom/down...o=file&id=1459
which fixes "dead zones" between the layers, keeping traffic flowing as the game progresses from the 41a to the 42a to the 42b, etc. layers.