low!?.....lol,hopefuly no one takes you seriously....
daily driving I am running 15-16 psi on a t3/t4 50trim and we still have snow

and once my fuel pump and 3 bar map are installed it will be up to 25psi (well and once snow is gone)
the ONLY sign of over boosting is the computer cutting it off.(over boost is just limited by the car electronics)
I have to ask why are you asking this question is there anything that makes you think you are hitting it when you should not?
if you are having driveability issues, missing ect at lower boost levels then that you have something wrong that needs taken care of.
and the reason for that is because that is the maximum the computer and map sensor can read and adjust for. the stock boost setting of lower then that was to keep cars reliable and lower warranty repair costs.
now a stock turbo is no longer very efficiant much over 14,15 psi, but can and will run at 20psi or a bit more, all day long if you change the nessesary things to allow to fuel and run that boost.
at this point turbo timming becomes much more important for turbo life. and you really want to make sure your engine is mechanical sound before pushing the envolope to far.
I started with a stock t1 car, and gradually built it up to 22 psi no waste gate daily driven car. on a engine that had 290,000 kms on it. it finaly dies at 310,000 kms and that is when I put in a stock t2 engine with the big turbo a ported head.