191 will be at the wheels, but it will be Horsepower, not Kilowatts. 191hp = 142awkw = ~212kw at the engine... so pretty normal.
All the Jap modded M35's have the FCON piggyback which is generally seen as one of the best, if not the best piggyback unit available... finding a tuner outside of Sydney or Perth is a problem though.
If you have a tuner nearby that tunes the FCON well, I say go with that depending on price. The eManage Ultimate is bloody good and a lot cheaper, or you could wait to see what happens with the stock ECU remap that a couple of forum members are working on.