I may be wrong about this, and someone can correct me if I am, but I believe that Gravely has had tunnel decks for some time now, in addition to the std X Factor deck design. Yes, my CUT has a wide discharge opening, and a deep tunnel. To answer both you and Razorblades (who I knew would post), it may be true that you can't say that all tunnel decks are equal, but all you need to do is look at the gravely design to see it isn't much different from the deck on my CUT. BTW Razorblades, I've also owned Toro tunnel decks, so I'm not comparing only Deere decks. Maybe I wasn't as specific as I should have been before, so let me say this another way- a tunnel deck can and will cut cleanly, and can handle tall thick grass as long as the power is there to run it, but when the grass is long and/or thick, and especially when damp, the full depth decks just handle the cut material better because there's far more room for it under the deck. You will normally see a much better discharge pattern (ie; even spread out, less to no clumping, and much more finely chopped clippings, though some decks like the V+ send the clippings out fairly long too) with a full depth deck because of the fact that it can handle more material at one time, providing the discharge openings and blades etc are all equal. There's a good reason that the full depth deck has become the industry standard on commercial machines. If the tunnel deck were equal to, or superior to a full depth deck for high material volume cutting at speed, you can bet the industry would be using them instead, or at least offering them as an option on commercial Z's, which they aren't outside of Gravely.