The only thing which ive seen done is blank of the compressor housing pipe and run the actuator pipe straight up to just in front of the throttle body. By doing this the waste gate will stay shut until the desired boost is built up to the throttle body and not just in the compressor housing.

Ideal when running a big cooler as you usually lose boost because of the amount of air needed to fill the cooler and pipes etc.

Apart from this I have seen what you described and it was connected to the dump valve vacum pipe as a way of keeping it shut on a diaphram dump valve?!?! Couldnt understand it personally but hey someone might explain!!