First off on the hopper extensions the regular extensions that taper out usually hold another 95 bushels. With that extensions it is usually another 17 or so inches tall. As for the straight bars on the rotor we ususally plant about 1000 acres of corn and we also have edible beans and we never have put the straight back on. An for the keystock grates I would say if you have them I would use them they do make a difference if you have them in.