Sharing here.

Live in an apartment at 20th floor. It's 22 floor apartment.
Water pressure on top few floors are weak

2 bathrooms.
Each having 1 pipe input, supplying to 4 taps sequentially. (wash basin, wall tap, toilet bowl and shower tap)

Dry kitchen 1 tap
Wet kitchen 3 tap (2 sink, 1 washing machine)
Bought Grundfos Scala 2 @ RM1700 from Lazada.

It's very quiet! Neighbors don't even know my pump exist.

Compared to many neighbours' pump where I know when they are taking shower. 

As Scala2 is an inverter pump, I was expecting water pressure to build up gradually when I turn on tap.
I was pleasantly surprised as water pressure is constant the moment I turn on my tap.
Seems like Scala2 had build up pressure inside the pump before you use.

All taps now have very good pressure.
Toilet bowl got refilled very quickly, so less time to wait between flushes.

Only slight pressure drop at bathroom when I turn on ALL the 4 taps.
There is no way the Scala2 sensor can sense the 4 taps as it only sees pressure from only 1 pipe.

Lastly, I am only setting the pressure at level 3 of 10.
Initial test at 10 of 10 appears to have "clear up" the pipes.
Now even not running the pump, water pressure is high than before installation.

I have also got the plumber to install by-pass in case I need to take down the pump for maintenance.

I am not too sure about the material.

However, as it's connected to the mains from the meter, the size over there is 1".

Installer had been considerate to use some rubber looking flexi hose, and he kept the connection to the pump with flexi as well.

If you look at the 3rd picture in my post, other than from the mains 1", after the by pass set up, it's the rubber like hose.