It's probably just an updated Musai, and if it's similar to the Tivvay, it probably has better MS storage/repair facilites than previous models of the Musai.
And to sorta repeat what Mark064 said, don't look into those extra thrusters too much. As far as is known, the Musai Final Production Type is just a newer, updated version of the Musai and we really know little else about it...