Is the port noisey or quiet? When the air speed gradient is that close, I’d be very leery about what the pinch is doing. You may open up the pinch and skew the air speed in other areas. JMO.
The intake port for those airspeeds was very quiet and that was reflected in those flow numbers. The port only had one semi turbulent area which was in the top of the port at the pinch. It wasn’t bad but I could feel and see it while I was checking airspeed. Since my bench is all electronic I will see turbulence with jumpy flow numbers that I couldn’t see on my liquid manometers. Liquid can’t respond that quick.