I searched through a lot of pages trying to find out how far below the cooking surface the tuning plates need to be for my cbss. I found one reply which stated about 2 3/4 to 3 inches below the cooking surface. I was going to start out at 2 3/4 and trim the plates smaller if I need to go lower. Can anyone confirm this or comment on it. My uncle is a sheet metal fabricator and I wanted to give him the measurments to cut them this weekend.