The second "plug" from the left of the top picture = no. That is the spout for the diverter valve, that I referred to earlier, and must be left functional as the diverter valve/blow off valve, keeps boosted air from packing up during closed throttle situations - without one, the boosted air would "hit a wall" when you close the throttle, and thus, stall the compressor fan in your turbo (potentially causing much damage).
The other thing which you need to plug, not pictured above, is the port on the primary intake manifold that the decel valve hose attaches to. Actually, I can see the silver colored spout for it poking up in the left corner of your second pic.
Here's what the diverter valve looks like inside -
http://forums.pelicanparts.com/porsche-911-technical-forum/71370-changing-930-dump-gaskets-pictures-galore.html