Carb tuning, larger accelerator pump nozzle?
That's decent vacuum.
FWIW as a comparison the Holley 80783 came with slightly over .033" primary IFR and .073 IABs
With .032 IFR a little smaller IAB is to be expected.
Cracking the secondaries. I think some people just go to far simply because they hadn't developed enough experience with what is useful and what can cause problems. If you find it needs a little more air to keep running, then give a 1/4 or 1/2 turn on the screw. On many carbs the bottom of secondary slots are higher than the primary side.