If you are fitting a shower power booster then do not forget you can take the SPB away with you when you move (unless of course the landlord paid for it).
A shower power booster is a permanent solution if you want it to be, but it can be fitted without permission as a temporary way of improving your showers and taps and it is WRAS APPROVED.
Cut out 110mm of pipe – fit the shower power booster – keep the section of pipe you cut out – reinsert the 110mm of pipe you cut out – reseal with a compression slip joint either end.
I find very few plumbing merchants stock compression slip joints, and those that do keep compression slip joints hidden away as if they are a secret fitting that is only for plumbers who are clever enough to know about them.
The barrel of the slip joint just slips over the pipe and into place when you need it, so fitting pumps where there is no play in the pipework or to replace the 110mm section of pipe you took out becomes so very easy.
We sell compression slip joints on the website, but do not forget that if you leave a SPB in place with no power supply it fails safe, so the flow without power is the same as before you fitted it.