FWIW, if you're using a speed density EFI system, it's recommended to have all the cylinders tied together one way or another. The guys who are doing speed density EFI systems with Hilborn or other type individual throttle bodies generally still tie all the cylinders together, even with something small like a 1/2" hose in order to get a decent MAP reading. I guess if you were using an EFI system that used a mass air flow sensor instead of a map sensor you could get away without it.