We recently had our plumbing replaced with PVC - the old copper pipes were prone to pinhole leaks. The copper pipe coming into the house is 1" and is still copper about 5 feet into the house after the shutoff valve (some of the original copper remains).
At that point it was converted to 3/4" PVC plumbing into the rest of the house, with the branches into the fixtures being 1/2" (where we used to have 1/2" copper).

Now, in most of the house, the pressure is slightly lower than before the conversion - is this because of the 1" -> 3/4" conversion near the source?