I have done zero to the engine.....yet! Just wanted to get the damn thing running first. It has the tune that came with the ECM I got from Modern Muscle( I think they changed their name recently???) The engine runs great as is. Not sure how much I will end up messing with it, time will tell. I did tell Dave when I bought the ECM that I was going to run a NAG1 though so that is what he set me up for.