If the manifold is really packed, then you need to remove the crossover AND the manifold to clean. But the car can run well with a surprising amount of crud in there. The important thing is to keep that sense line open all the way to the Alda. The Alda is a barometric control that increases fuel in response to turbo pressure. If it can't sense pressure in the manifold, the turbo becomes a boat anchor...lots of air, but no increase in fuel to match. So if you still have low power, you need to recheck the port and switchover, and make sure that the associated lines and rubber connectors are clear. What you can also do is spray carb cleaner into the sense port to clear the crud in the immediate vicinity. Just do this while the car is running, and only a bit at a time, you don't want to fluid lock the motor.

I would also suggest removing the sensor directly above the port and doing the same deal. When you pull it out, you will think the business end is smooth and black. But when you clean it, there will be a tiny hole in the face. You want to use sensor safe carb cleaner to blast the hole clear. This is the overboost sensor, which controls that vacuum switchover relay. What it does is cut fuel if the boost becomes too high, as would happen if your wastegate became stuck. It's a safety that you probably never need, but good to have it working. It's also another hole that you can use to spray cleaner into the manifold.