OK, you asked for it, here is some more information about my house and system:
I live in the foothills east of Sacramento, CA. My house is on a hillside facing west with a walk-out basement. The top level is 2120 sq ft. It has vaulted ceilings and a lot of windows. When I built the house I left the downstairs unfinished. The Title 24 for the top level lists a total heating load of 77,351 Btu/hr and a design cooling capacity of 53,507 for a conditioned area of 21,974 cf. The winter outside design temp. is 20 F and summer outside design temp is 97 F. That is what the system was initially designed for. I hired a contractor to provide and install the system (including all the ducting). I have since finished 363 sq ft of the downstairs and eventually will add another 367 sq ft. Two actively controlled zones are upstairs and the downstairs is one actively controlled zone. I normally leave the downstairs set to unoccupied and only condition it when I have a need, the upstairs zones are on a scheduled program. There is 1 20"x24" return (18" flex) and 2 14"x20" returns (10" flex) upstairs. the downstairs has a jumper duct to get around the door. The upstairs main living are (zone 1) is 1540 sq ft and has 2@5", 1@6", 6@8", and 1@10" supply registers. The master suite (zone 2) is 580 sq ft and has 1@6" and 3@8" registers. The downstairs (zone 3) has 2@6", 2@8", and 1@10" supply registers. The 10" register is temporary until I finish the downstairs.
The new contractor took measurements with a magnahelic but didn't give me the results, I have asked him for them.
I don't know it they ran the system with the blower door off. They did run the system with one of the large ducts off and the pressure was just below 1 (.93 I think).
I will try to take pictures of the ducts this weekend if I get a chance.