I'm taking off my stock intake and towards the back there is a silver bolt looking thing with a tube going into it. I have no idea what it is and therefore don't want to mess with it, which is where you come in. Can anyone tell me what this is?

 

It's a vacuum source. When I don't have an L03 anymore so I use it now for hvac. I should probably use the front TBI hookups for a more constant vacuum. I just liked how there weren't 5 vacuum hoses coming from the front of the TBI. Now it's only PCV and sometimes cruise control .

 

Its the manifold vacuum mostly for the HVAC system, you need that for your HVAC to function properly. Just make sure the hose connected to it is in good shape (no cracks) and that it is hooked to the HVAC valve (small conical shaped valve with three hook ups).