high water pressure - pipes judder when taps switched off

[dandt]

Hello
I am staying at my mothers for a few days. I am reasonably competent but need some quick confirmations.
I noticed when the mixer taps in kitchen and bathroom are turned off there is a 'kick back' in pipes. My worry is that this will eventually cause some damage/leak somewhere
I know form the past the house does have a high incoming pressure of at least 6 bar (may be higher)
I noticed the stopcock is only on a quarter of a turn (left that way by the last person who did a plumbing job)
Now I know there is a subtle difference between flow and pressure (ie pressure problems cannot be solved by reducing flow)
I opened stop cock to 3 half turns. This cured the problem at each tap except that when taps are turned off in kitchen you hear a shudder elsewhere in bathroom
I suspect the answer would be to fit a pressure reducing valve and set it to 3 bar
I did this in my house when I was fitting a mixer shower.
Does this sound like the problem / solution. I dont want to go to the bother of getting this work done if its not relevant. Also her mixer shower works fine as it is. I am only concerned about potential damage from judder
should I be concerned?
many thanks

 

[bolshy]

Fit a mini arrestor to the pipe near the source of shock. Make sure it's for potable water and wras approved.

 

[dandt]

thanks
I will obtain and fit soon
in the meantime how likely is it that judder will damage pipes
and will a quarter turn open stopcock starve any device such as modern boiler (everything does actually flow fine)
thanks