It really depends. Hook a pressure gauge up to the line coming off the rear of the intake manifold. If you have low boost pressure (5-8 psi) then your wastegate spring has lost some tension, and you can tighten it up. It's a whole lot easier to hook up a manual boost controller though. Do a search and you'll find some posts regarding this.

The procedure is not dangerous as long as you stay within factory spec and have an accurate pressure gauge hooked up, so you know how much boost pressure you're running.