Best EFI for a 408?

The most important thing with aftermarket FI is customer support. I have a Fitech unit and the problem I have had, they helped, but there is so much info they don't tell you. You can't have progressive linkage with the 2 throttle body setup. They never told me. They don't give you any idea about what the parameter readings should be. Maybe others can chime in with their experiences. By the way I have a 472 hemi with a moderate build and prior to FI had 2 four barrel carbs. It ran pretty good with carbs but always looking for improvement.