Many factors to this....
How much do you like your engine ?
Do you like smooth progressive power or full on see-saw ?
What fuel do you want to run - super or normal ?
Power figures are very often grossly excagerated... lots of standard 150s that hit the rolling roads make anywhere between 180-195...
But the 1.8T with small intercoolers never really show their full potential on rolling roads... on the real road the intercooler can be kept much more cool.... so making much more power...
A stanadard car shouldnt really run more than 1.0-1.1 bar (almost twice standard boost) because of things like high EGT (exhaust gas temps) which are really bad for the turbo... the car measures all this and if it sees too high then dumps fuel... so fuel economy is bad and power drops.... and intake temps climb and again power drops.. knock starts..ign timing is pulled.. and again you loose power...
So as the old addage goes... LESS IS MORE....
Its why things like stage 2 exist.. if the hardware is modded then you can go stronger...
J