I'm not sure of other brands, but the 100% carbon fiber Competition XFS Rickters have no tube for either scupper. They leave the tubes out of the comp models to save all the weigh they can. The mid-shaft bulk head doesn't go all the way to the bottom of the hull so the water runs back to the scuppers fast.
I replaced the right side scupper with the big Thrust ball valve in our ski. Just remove the scupper ring (hardest part of the install) and epoxy the new ball valve in. I also put a golf ball size ball of epoxy 3" inside the hull to support the end of the ball valve. There is no room to replace the scupper with a ball valve on the left side (Exhaust pipe in the way), so I'm going to do a custom arrangement on ours this winter . Scuppers flow more water so they work great in competition, but for a lake ski I think a ball valve is safer.