My old intake had those. You can run a hose there if you want. It's supposed to kind of "even out" the temperatures between the two heads. If you have an overheating problem, it may help a bit.
I didn't bother with it. I wanted to, but in the end, it was more work than I thought it was worth. Plus, the hose would probably get in the way of the distributor.
Matt :kirby: