I am still using the stock oil pan modded to keep oil from sloshing around during cornering. I read that a well known drag racer says that even though you get a 7qt oil pan the oil pump can suck the pan dry cause our heads hold so much oil in them, he went on to say that the windage tray helped to supply oil to the oil pump. I would guess it's because it directs the draining oil down into the pan instead of being whipped around from the crank.