1st time homebuyer in rural area...need to increase water pressure, especially for the shower.I think it was set to 40psi, but the home inspector said not to go above 50psi (?) and showed me some nuts to turn on the switch. Also, the shower has pressure fluctuations (need a constant pressure switch (?), and noticed spitting--or at least it sounded like it coming from the upstairs faucet (air in line?). Please advise...thanks!