I'm a dummy, so requesting clarification:

If I put a mityvac on ALDA, it should be able to hold 10 pounds of pressure?

This car is still running a vacuum wastegate. I've modified a previously-owned w124 300d with a pressure wastegate. In that previously-owned car, the waste gate was stuck open allowing zero boost...zero boost = ran like a DOG. My current situation is underpowered, but not as underpowered as the stuck-open waste gate (as memory and the seat of my pants remembers).

Thanks!
Brad