What do you want to know? I certainly am not the authority on all of the different stand alone efi systems available, but I can tell you if you’re interested in individual cylinder fuel and timing control you are going to need one of the more advanced ECUs. Holley dominator, megasquirt, motec, and AEM infinity just off the top of my head. I’ve personally used and tuned the AEM infinity (my favorite) and the holley dominator.