The LMM engine you have is the most powerful diesel put in a pickup, at 365HP. Stock, on a dyno, it shows about the same rwhp numbers as an original 426 Hemi, ~325rwhp.
Most everybody loves their LMM's.
Things you need to know:
Smog testing is coming for the diesels. Be careful of removing components. Do not discard.
You do not have a diesel emissions fluid engine, but you DO have a Diesel Particulate Filter. It is self cleaning. You will see a light on the dash when it's cleaning. Do not park over dry brush with the engine running.
If you "re-tune" the engine computer, GM can tell, and can void your powertrain warranty. Not sure if there is a 100% fix for that, but trust me, people are working on it.