[LazyPup]

The reason you are not finding a PRV (Pressure Reducing Valve) is because a PRV is not installed unless the incoming pressure from the municipal main is equal to or greater than 85psi.

For the purpose of selling the house you are only required to have enough water pressure to meet code minimim.

Under the International Residential Code the minimum permissible "Static Pressure" is 40psi (IRC-2903.3) while under the Uniform Plumbing Code the minimum permissible "Static Pressure" is 15psi. (UPC-608.1).

Most home supply centers now carry a small pressure guage that has a female hose thread fitting attached so that it can be screwed directly on an outside hose bibb or a laundry sink faucett that has a male thread on the end of the spout. (Often these guages are called Irrigation pressure guages and Typically you can buy one of these guages for about $15)

NOTE. Static Head Pressure is the pressure on the system when there is no flow of water. When all faucetts are closed and there is no flow the pressure is equal at all parts of the system.

Another simple test to see if you have code minimum water volume is to place a 5gal. bucket under the tub spout and turn the cold water line on full force then time how long it takes to run 4gal. (Code requires a tub to supply 4gal/min while the shower head is limited to 2.5gpm.)