A which plug is this question and VVT Question

[jrd450r]

I have had my car (rb25 s13) all apart for a turbo, injector, intake manifold, etc upgrade and I am left over with a plug and not sure where it goes. This image is not my car but I am using it for reference, can someone tell me where this goes or what it does? It is the dark blue plug.



Also I don't belive I ever hooked up my VVT when I originally wired the car atleast I am not sure since it was so long ago, can someone point out what needs to be done to make sure that it works properly so I can check and see if I did that. Any help is greatly appreicated and once I get the car started ill be sure to post pics and videos.