I have a B7100. On top of the engine (head) there is a "down spout" sort of looking thing with a hose attached to it (my B5100 has this same thing). The hose basically just hangs down under the tractors. I was assuming it was some sort of vent. Anyway, on the B7100 this hose stretches all the way to about mid frame and exhaust comes out of it!! I mean A LOT of exhaust. It's like having an extra tail pipe. Exhaust does not come out of this same hose on the B5100. Any idea what's going on?????