I did some searching around in the forums but didn't really find what I was looking for so I apologize if this is already answered over and over. I have two pipes that I think are a Billiard and some kind of Bent Apple. Forgive my complete ignorance about shapes. I spent some time just looking them over and one thing I noticed is that the draw on the Bent Apple is WAY easier than on the Billiard when they are totally empty. Is it possible to switch out stems to be a easier/harder draw on the pipe? I assume it would be, but I don't know if the bowl would restrict it anyway.