Some have issues with the stock turbo dropping boost others don't.
It comes down to the exhaust.. If the dump pipe is not quite right or the cat is restrictive it will drop boost.
If its dropping boost, fit a closed loop ebc and it will hold boost.
On a tuned ecu with ~1bar (providing its holding 1bar), good exhaust, fmic expect 170-175rwkw.
Upping the boost over ~12psi doesn't do a great deal for the top end (I picked up 12rwkw going from 12.5psi to 1bar on the stock ecu) even if it is holding boost but it really does improve the mid range a hell of a lot.
I ran 1bar for ~4years. Turbo came off and was still in good nick.