First of all I apologize if this is the wrong place to ask this. I didnt see a section specifically for general questions.
I know this may seem like an ODD question but I am split between trying my hand at diesel tuning or picking up a tuner from one of the Pro's out there. I have been tuning gasoline stuff for a while now but I am a green horn when it comes to diesel stuff. So here is my question(s). Are the stock tunes that are found out there for the LML on sites like 4share the actual factory stock tune as GM would have loaded? Is there any loss of information or data when these ECMs are read via j-tag (or however they are doing it)? I have seen from time to time when updates come out they say "new tables found!" Does this mean the tables weren't there before or does it mean they have always been there but are just now able to be modified? I guess a simpler way of asking would be, "If one were to compare GM's tune file against one pulled from a J-tagged ECM...would there be any differences?" Assuming one could do an actual or true comparison? I hate the idea of writing over my stock tune and not being able to read and save it first.
As a side note, I have yet to find a stock tune file for my truck.
2014 GMC 2dr 4wd SLE LML
Most everything I can find is 4dr stuff. Still a little unclear why they seperate tunes between cab styles and option configurations but thats a question for another thread .