That port underneath the throttle body...
 

I'm gearing up to install my DIY turbo on December the 13th, and I'm just going over my list of everything that needs to be done. So I have a question about that rubber hose that hooks up to the NA rubber intake, and then hooks below the throttle body. How important is that port? Does it have to be hooked up to the intake pipe, or can it just have a breather on it? I have a full MAF delete on my car, so air metering isn't a problem.

Thanks folks!

I would imagine it needs to be on the charge pipe since when your IAC opens, it'll be sucking air from outside the charge pipe otherwise. Might even be a potential boost leak when if the IAC dosen't fully close under boost.

If you have an aftermarket ECU that doesn't require an airflow meter, then you can throw a filter on it and call it a day. Otherwise it needs to be plumbed into your charge pipe.

But does the IAC open at all (I know it's not needed for it to unless idling, but who knows what happens) under boost? Maybe it can get pushed open? I'd just be worried about a boost leak

I've heard it argued both ways. Mine's open because it's simple.

I would like to see someone link to or come up with a conclusive test.

worst case if it does leak you can go to the plumbing section of your local home depot and pick up a nice one way valve for about 10 bucks. they are brass and have a rubber lined plunger. I'm not exactly sure what they are used for, but I saw one there and thought that this exact circumstance would be a perfect use for them. I didn't hook the IAC up to the charge pipe on my new setup because eventualy I'll do a sheet metal mani with a larger throttle body. Boost leak is def something that concerned me in the interem though. So I figured a one way valve and a small air filter would do the trick. then while buying a new dehumidifier I stumbled across some in the plumbing section.

no leak boost

Well I'm probably going to route the iac hose onto the charge pipe since I'll need a port for my BOV, so I might as well just add 2 ports.