My local (large) PW dealer told me you can't change the PSI on a PW'r by changing the nozzle size. All you could change was fan degree. His "Top" 25 year sales person told me the first number in a nozzle chart has nothing to do with GPM. I tried to ask why it matches the number on the 4,000 psi column and he said it was just an arbitrary number? Since then I will buy small items if I can't wait. Otherwise since I get parts in 2-3 days I buy on line. Even the head of the parts department could not read a nozzle chart.
I swear this is true.