Yeah, my first guess was that the previous owner had probably messed with the actuator adjustment. Most likely, he left the spring pressure relatively high which indicates two things at least. 1) He had been running relatively high levels of peak boost on the turbo. 2) Once spring pressure is set at that particular level, then as a practical matter, it becomes nearly impossible to set peak boost lower than that, no matter what you do with the boost controller, or the ECU.

The first thing that you will want to do is adjust the WGA to its base pressure level. This base level is usually somewhere between 11-12 PSI on a stock factory actuator. That is assuming that the actuator is a stock one and hasn't been modified.

It may be that he installed a FP 18, or 25 PSI actuator on there. They look real similar to the stock piece. Also he could have modified the actuator by cutting some threads off the threaded end of the actuator rod.

Either of the two FP units would exhibit a higher base spring pressure than an unmodded stock actuator. The 18 PSI FP actuator has a base spring pressure of approx. 14-15 PSI. The FP 25 PSI unit has a base pressure of about 18 PSI.

So, since we are not sure what is on there presently, that is why you need to adjust the actuator to its base pressure. Also, if we adjust the rod(by turning just the turnbuckle, sorry) to where it freely slides on and off the peg on the flapper valve we start at the beginning. We establish what the base pressure of the particular actuator is. And also this helps determine whether your high boost scenario is due to the WGA, or alternately the form of boost control. Because if we can't lower spring pressure down to a level lower than the current one then this would indicate either that you need a new actuator, or that something else, not actuator related is wrong with your boost control circuit. Thus, it will give us a good starting point in the quest to find the source of your boost problem.

Make sure that I am online when you start messing with the thing, OK? I'll try and help you sort through the process.

EDIT: You may want to post up some pics of the actuator as it sits presently, mounted on the turbo. Take a shot at the turnbuckle and how many threads are visible behind it. Take a shot of the actuator canister itself. Then finally take a shot of the point where the base of the actuator rod enters the canister. Also while you are at it take a shot of the MBC mounted in the engine bay.