A picture is worth a 1000 words.
Redline of Australia is the original manufacturer of the IR manifold with the built-in vacuum box. Its a 2V manifold with enough "flange" around the runners to seal-up around the ports of a 4V head. It uses intermediate adapters allowing it to be configured for either IDA or IDF bolt patterns. For that reason, its a tall manifold.
The Borla manifold below has a similar box, but its not the same manifold. I'd guess they've designed their own manifold. You can see a corner of the box which has been added in the middle of the valley.
Below is the Aussie Speed of Australia IDF manifold, which like the Redline manifold is a 2V manifold with enough "flange" around the runners to seal-up around the ports of a 4V head.
Below is the Hall manifold being used for IR fuel injection.
Below is the Hilborn "3 piece" EFI manifold for small block Fords. It provides manifold and throttle bodies all-in-one. Each bank of throttle bodies has a one piece shaft for the butterflies. Only linkage is that connecting one bank to the other. This gets my vote.