So what to do?

My thought is that the Torbeck valve I've got is inadequate for the
water pressure (ISTR it's a fairly standard 2-3 bars) - I can't
particularly rememember any issues over pressure rating etc when I
fitted it, and would certainly have been wise to it had it been
mentioned or whatever. Are there specific versions for high and low
pressure or do they have swappable components?

I'm thinking of buying a new Torbeck valve and fitting that from
scratch: does that sound sensible or am I missing something?

Thanks
David

The service valve could be contributing to the noise if it is partly closed
I guess.