thanks for trying to help! pressure seems fine. The problem started quite a few months ago - may even have been when we had a 2nd toilet installed. It certainly much worse now, it's very loud. I had a Belgian plumber look at it and he simply couldn't figure it out.
Whilst running 2 taps at the sametime, or one tap and flush the toilet I get a howling sound which I cannot for the lifer of me locate, but it's loud. What's happening? thx!