I have a 2011 LML with PPEI tuning. I have always been curious on how it worked and I have always wanted to tune my own vehicles. I have several diesel trucks in my business so i would like to learn to tune them as well. The ultimate question is, where should i start? My oldest diesel i have is an LLY. I just want to start slowly and make slight horsepower gains. I plan to slowly work myself up and learn as i go. This may be a stupid question, but how do i add horsepower to these trucks? I assume through fuel output and timing. like i said, i am very new and have played with some LMM files and i learned how to disable the EGR and the DPF as well as the turbo vane positions to make them rumble or hiss at idle. Sorry in advance for the stupid questions, just bare with me!