Cheap flexible tap connectors - warning

[John D v2.0]

I'm sure you mean flow rate not static pressure there, which a prv shouldn't make a big difference in itself.
Regardless of that, you need a good "supply" of electricity for an electric shower, a good cold flow rate won't help you much there (unless you're having to have the setting fully to the cold side to stop the shower being too warm)

 

[chrisw99]

Don't suppose there's a DIY way to test the static pressure without having to fork out £20 for a pressure gauge?

 

[John D v2.0]

Fork out 20 pounds for a pressure guage from somewhere with a generous returns policy, measure your pressure, then return the gugua!