i did experiment with cutting baffle shapes in the rings, wrapping a cut up mousemat around the inside of the chamber (to dampen any noise that hits the can wall), stuff like that.
dont think it did all that much, a decent sized can and an action that's quite enough for suppression to make a difference is pretty much all the way there.
besides, anyone you shoot silent or no will be coming right back for you after he's respawned (assuming he didn't scream hit at the top of his lungs then whisper "he's over there" to his buddies as he walks off)