Yes, greasing the underside of the endplates will help eliminate the noise. If you look at the undersides, you'll see an indented section with rings around the center hole. Put lithium grease (from the tube, not spray can) all over that section. You should also put the grease around the sides of the top of the struts. These are the parts that actually make the noise in the first place. They have rubber bushings in them that expand when you turn the steering wheel, and rub against the undersides of the APR endplates. Turn the wheel all the way to one side and put grease on the side of the struts that stick up, then turn the wheel all the way to the other side and do the same.
BTW, you don't have to pull the bar forward when tightening the bolts. It clears the firewall/windshield cowl fine. The only important things to remember while installing are to have the car on a flat, level surface, and to have the steering wheel pointing straight forward. Otherwise the bar will be misaligned on the struts and cause excess stress on the strut bolts.