Especially if you keep the 2 levels/planes separated with a spacer, check your plug coloring with clean plugs after a few runs. If you see a slight but obvious coloring pattern showing the plugs being fed by the upper level/plane a bit darker than the ones fed by the lower level/plane, you should benefit from adjusting the jetting from side-to-side by a couple of numbers. Lean the upper level, richen the lower level or split them. My theory is that the lower level contains a larger volume of space and reduces the vacuum signal, requiring slightly larger jets to compensate.
I found this pattern on a Weiand Stealth I ran for a while and it seemed to help ET's by about .05.
Being a "modern" manifold, I don't know if the Air-Gap may have built-it features to compensate for this. But plug coloring patterns would help determine that, if the carb is jetted the same side-to-side to start with.