our 86 isn't all that impressive in corn, this is what we run, you may be different, wet(28) 3 is max dry (17) 4.5 is max our 86 is a monster in soybeans, the faster you drive the better it works, we have the s cubed rotors, if you do not you will have problems, and the newer style 973 with terrain tracer, if you have any uneven ground the terrain tracer is a great deal, we don't run too fast, about 3 pushing a 22 fter, but that is because our head can't cut much faster, combine never makes a grunt or growl, this is in good dry beans, wet stems cause trouble we are also slow because dad drives the combine