If you look at some of the op manuals and the service mans. this seems to form a narrow at front-wide middle - narrow rear setting that takes loads of HP. We have done a lot of work here and found that about 5_16" at front is about all that works here with out robbing HP. If needed we add filler strips at the front to make more aggressive threshing if needed- w_o hp consumption. As in all things conditions dictate diferent results. After all I don't see how you guys run your Gleaners up side down!! I tried that once and the insurance agent went beserk!