High pressure water noise

[Lord Flashheart]

Since going from tank water to combi boiler, my mum's taps have become really noisy. The isolation valves are full bore and fully open, but the noise is still quite annoying at night particularly. The local pressure is high at about 4 bar, so I'm wondering whether there is a cure. My first thought was to fit a pressure reducing valve where the mains comes in, but as there are two bathrooms I thought maybe it would be better to fit something locally to the basin itself. It really is the basin that needs sorting because of night time use after the loo. Would a pressure reducing valve even sort the problem or would stepping down the pressure by the tap make it even worse?

[OutInTheShed]

Read the spec for the combi boiler, it may require a pressure reg valve?

4 bar is not high. Some places where there's a water tower on a hill, you can have 10 bar, especially in the middle of the night when flow is low.