You mentioned that you were going to test the street pressure. One way to test the water pressure is with a simple to make, and cheap, gage.
This is what I use.
I bought a pressure gage at Home Depot in the well pump section, then connect the gage to a 1/4" to 1/2" black coupling (I had to buy at the local Service Star hardware store) then to a 1/2" to 3/4" brass reducer and then finaly to a 3/4 to 3/4 hose connector.(make sure to use pipe tape at all the conections.)
I think it was less than $12.00.
Connect the gage outside to the hose spicket and turn it on all the way.
This should give you the pressure coming in from the street.
I have been told by a Plumbing Inspector to plan on a 10 lb. drop per floor.
Have someone flush the toilets, and run the fixtures, one at a time, and check to see how much the water pressure drops.
You may not have a large enough line coming into the house.
Or, if your community is like mine in New Hampshire, they may have turned down the pressure to try and conserve water.