jasons

its the torque that slips the clutch. rather than power.

if its a 16v it will have a 3bar map senor, so you can play with the boost a fair bit.

A good tuner will limit the boost/torque lower down, say till 2.5k rpm, then start to let it loose, this way you will acheive the higher end power but without destroying your clutch and box.

The 150bhp 1.9 is really only good for 190-195bhp anyway.
The turbo is not the largest to run big boost at high revs.