Gang, I have a 2007 3520 and maybe it is me but I don't notice the exhaust smell that bad with the underhood setup except if the wind is blowing back at me. I use my tractor a fair amount, but maybe I am conditioned to it. Heh. If I fire up the dozer with a vertical (obviously), now that make you stink in about 2 minutes, same for our older 820 (also vertical). I was considering the vertical exhaust for the 3520 at one point but then decided I didn't want to spend the money since it didn't really bother me. As suggested, I would try the standard setup and see what you think. Also, my loader is all sooty just like everyone else, but its a tractor not a driveway queen, so that doesn't really bother me either. That's the beauty of choices though, and what I like may not be what you like (well, except for the Deere part :thumbsup: )