to shimm wastegate or not to shimm that is the ?

[cre]

Shimming the wastegate is a terrible idea, a crap practice and something which needs not be encouraged. You reduce the lifespan of the wastegate and you reduce it's range of motion creating a potential for boost creep and possible damage. It's an old hack which was poorly thought out from the very beginning.

Just build a manual boost controller. They're damned cheap and they're tunable.

http://www.gusmahon.org/html/boostcontrol.htm