K, we've got great water pressure, so I think it's a matter of the setup you have right now. We use a combi-boiler for all our water and house heating, which shouldn't be confused with a power shower. My preference, I love a combi boiler. Basically it's a gas boiler that will only heat the water when there's demand for hot water, so it's not sitting in storage in your attic (or wherever) waiting to be used...the "standard" boiler heats up water and holds it until you need it. I don't find that as efficient.
As far as power showers go, they are pumps which assist gravity-fed water supplies, such as the "standard" system (water storage in the attic) I mentioned above, and are not visible unless your plumber has played a cruel trick on you. Since we don't use gravity-fed water, we don't need one.
I think Mr_Val's "power shower" is actually what I usually think of as being a "geyser" shower, a unit just beside the showerhead that heats, but does very little pumping except to restrict water flow to make it "feel" like you're getting more water.
I'm not sure I made sense in this. When you come over on the 5th, I'll show you what I mean.
But generally, I find no water pressure probs except for the same percentage as what happens in the US. In other words, it's not a country thing...but up to the individual house. I think it's just your in-law's house.