does anyone know what i can flash my ecm with to run custom operating system there isnt one listed on my list for that one i like to run some sd to try a gas milage tune up or can i just change some settings with the stock operating system and do it that way figures the one i want to test with (my avalanch) i cant get a operating system that matches i have a lc1 with the air fuel gauge so i can watch it when driving to make sure i dont damage it thanks in advance for any ideas