Using Infinity 58MVB60 air handler installed the static pressure showed by Infinity thermostat display is 0.9 – 1.0. It seems a bit high.
The air duct (supplies) sizes I have calculated for the 600 – 700 CFM by using well know HVAC Calc software tool.

I removed the air filter insert from an air purifier GAPA body, keeping the filter compartment open letting easier for the air to get into the air handler.
I was surprised that the static pressure went up by 0.1

It is an old house and the ducts installation was a real pain.
But I want to get the pressure down to appropriate 0.5 level or so.

My question is should I add more returns or more supplies?