I have a New Holland WM25 with forward exhaust. I breathe exhaust, yes, and I HATE it. I keep thinking I should build a vertical extension, like Sno said. My previous tractor, a little Kubota, had a vertical stack and I was perfectly happy with it. Yes, it could catch tree branches, but I have a ROPS and canopy anyway, so it wouldn't be any more of a problem than they are. Besides, they're my branches, I just cut them down if I'm going to run into them again.