What to change and how to change

First off hello im new to this forum and new to tunning with efi live by myself i always had it done but i wanted to get more hands on. i have a 2003 lb7 with a manual trans and im trying to tune it i got the stock tune pulled off and saved and i am wondering where in the hell do i start i have absolutely no clue i looked at another guys tune for an lb7 and i find myself just changing numbers to his but i wanna know what exactly i need to change reasons why to change it and how to change it like i said im new (when i say new i mean i had to read on how to get the dang stock tune off the truck new) but i am willing to learn as much as possible and from reading around and looking at posts you guys seem to know your stuff. any help is greatly appriciated thanks in advance

Its mostly knowing how a diesel works and knowing what each item that makes the engine run. Many make just slight changes to the most common used tables and log it and see what is improved or has lost. Somewhere on here is a link to some books that may help. Use the search tool and search for ' books '. Check out some Duramax Forum sites for possible EFILive help. You can take the tune you have bought and maybe take the tables in quarters and increase the stock tune a quarter to see the differences in slight increments. Good luck

Brian