I have never seen anything in that hole on a vehicle or in microfiche. Assumed it was/is a weep hole for whatever water/oil gets captured by the guard.Where do the two little ones get installed? Also, will the driver one work with headers? My passenger side one was cracked, it looks like some kind of support was missing from the frame to the hole in the bottom of that depressed feature? Any damage on these? Is this just for splash, or will it help draw engine air away from firewall because it directs vacuum, like a Venturi?