2007 GT

I replaced my stock airbox. I am enjoying the new air filter, it's great.

I am just not sure what this line is for in picture number one?

Not the brake booster hose, the little metal nipple up under the hose, next to my thumb.
It used to plug into the black rubber boot on my stock air box setup.

I put a tiny little air filter on it. This filter can both push or pull air through it, no resistance either way.
I only hooked this up to keep it from sucking any dirt in, until I can figure out what it actually does.

Thanks