Originally Posted by
Danny.
If for instance you get a low result of say 120-125 across all 4 cylinders what could this mean?

Nothing. Your engine is wearing evenly? The actual figure is not important, UNLESS they're all 10psi or something.
If they're all 120-125 then thats good I'd say!!
Squirt a bit of oil down the bores through the plug hole and do another test, see if they increase a bit.