Steve,
the boost profile is load and revs dependent so it can and does vary.
try WOT at 3 krpm , vs WOT at 5krpm and they wont peak at the same psi. (well APR doesnt anyway, at 3k I get 21 ish peak , at 5 k itll be 17psi)
on mine (apr not revo) , the boost peaks very quickly to 21 ish then almost instantly starts to settle at around 17psi.
Theres a graph on how the software peaks then troughs to find the stable boost pressure somewhere on golfmkv...
I think REVO has the same 'profile'
Worth also trying on/off on the throttle to see how the car reacts
You are starting to see how useful this guage is going to be for you