So I'm reading in Diesel World magazine that a Power Pup tuner adds 58 hp and 114 ft-lbs of torque on the dyno , which makes the new Lmm 363 hp and 757 ft-lbs of torque . what I dont understand is , isnt the Lmm already 365 hp and 660 ft-torque ?

Factory numbers are rated from the flywheel. It looks like those readings are from the rear wheel. You lose power as it goes through the transmission and rear axle.