Intake vent hose?

[Project RPS13]

While installing a k&n filtercharger into my 1990 fastback, i realized that there was no vent hose on the stock airbox. (perhaps removed by the previous owner) I believe it is supposed to be located right next to the temp sensor. There is a small white tube protruding from the airbox but no hose attached to it. Now, on the k&n filtercharger there is a vent elbow where this vent hose is supposed to attach to. I guess my question is where is this vent hose supposed to go from the airbox/filtercharger? What is the purpose of this hose? Is it neccessary or can i just plug up the vent elbow on the k&n? Please help!



Thanks