If you are not running small wire concaves, you will definitely need cover plates in my opinion, and even if you are running small wires, you can still run one or two cover plates if needed. I always end up running the concaves pretty much tightened up and then adjust rotor speed as needed. Also make sure that the bottom shoe seive is about one quarter inch open. If you start to get grain going up tailings, then open it up a little. Keep in mind that the faster the rotor speed you run, the easier it will be to throw grain out the back. Gorden bars would help to thresh tough grain more, but if you also combine beans, I don't think you would like them in that crop. They also take more power to run. I would just stick with the regular pads and make sure they are in good shape, if they are wore down, it will definitely affect performance in grain. Make sure you have the concave zero point set correctly also.