I am confused as well. After re-reading all of the posts, I just realized that
@SMalafy is the Post starter. He mentioned that he had a boost gauge. You did not, but I was assuming that you were using a boost gauge to help diagnose your problem.
I think you should start your troubleshooting from scratch. You are focused on a malfunctioning wastegate without any real reason for it to be suspect. You have a boost gauge, but you haven't installed it. You need to install it.
As I mentioned before, there are many things that can limit boost pressure. A faulty wastegate is only one of them. Limited fueling is more often the case.
Have you checked for and recorded any trouble codes? This would be a first step if you haven't done so. The ECM has the ability to detect fueling problems or sensor problems, and if they exist, the ECM can and usually will de-rate the engine fueling. That alone can cause unexplained limited boost pressure.
Check for engine trouble codes and post them. Install your boost gauge. Let us know boost readings related to engine rpm and engine load, and what your driving condition is when the boost pressure is limited.
- John