Quote Originally Posted by B.P.U Subaru
If the wastegate actuator is tightened, more boost will be required to open the wastegate. Thus the turbo will build more boost before it is relieved. I haven't heard about surge, but I do know some people who occasionally get spikes on cold days.
Yup. Holding it closed will make it spike and if you adjust it too far you'll get surge when you're tooling around town at half throttle.

You could always do the GM boost solenoid mod, for $15 you'll get slightly quicker spool and much better boost response.