Not a clue what those pipes are for … I missed them when I built the engine for my Dragon kit, but looking at the photos of a restored vehicle I used for that, I see now that they probably should have been on that engine — though side-by-side under the carburetor rather than one above the other like you have them here.
Ah, yes: page 22-4-56 of Panzer Tracts No. 22-4: Mittlerer Zugkraftwagen 8t (Sd.Kfz.7) by Jentz, Doyle and Friedl does show two pipes there, side-by-side. The outer pipe is plain, the inner one is corrugated for most of its length. Both run forward from under the carburetor, bend to the left, then go on to the other side of the engine and bend towards the rear (where they disappear out of sight). If you want I can scan the photo for you.