(2)450 DP's vs (2)750 DP's
In my experiance the idle circuit doen't initiate like a velocity based circuit. ( I guess that's because it isn't. )
Applying that to the graph, modifies like so.
I know I've told the story of modifying my first 3310 and not being able to drive home until we put wires in the IABs. My first and most enduring lesson idle slot exposure, adding air at idle to close the throttles more, and IABs.