i purchased a used manual boost controller off ebay and came with directions. i understand the bearing side goes to the vacuum source and spring side to the internal wastegate. but what about the nipple that had the hose originally attached to the wastegate? just plug it? i did search and thats what im concluding to. id hate to do it wrong and have like 30+ psi or boost leak

 

The nipple on the compressor housing that was originally going to the wastegate actuator should either be used as your vacuum source or plugged.

I would use it. The boost produced right at the outlet to the turbo is greater than the boost the engine will feel, and the larger the boost signal the more precisely you can control it. I also wouldn't want to put vacuum on the valve or actuator. I don't know if that might damage them over the longrun.