I have had increasingly worsening pressure in my hot water lines in my house and now have a very annoying whistling coming from the kitchen faucet when I turn it on which is getting worse. I replaced all the galvanized pipe from the hot water heater all the way to the other side of the house where it goes up into the 2nd floor wall. It is somewhat better but not much. Where can I expect to look to solve this problem? I was hoping not to have to tear up the wall but I guess it's not looking promising...