I realize there are a lot of tanks set up with the uniflow linked to the pickup on a clunk tanks. I'm wondering if that might be a reason for some mixed reports regarding how well plastic tanks work for stunt?
As I see it, if you tie the uniflow to the clunk, every time the clunk moves, your relative fuel head changes, and therefor, your run also changes. The whole deal with a uniflow is that where the end is, inside the tank, is the place the system sees as the center of the tank. If it's moving, then the center of your tank is also moving. It may be hard to get a really good run with that happening.
By routing the uniflow, by itself, to the inside wall of the tank, the uniflow referance does not change when the pick up moves. A better solution that should give true uniflow performance to a plastic tank.
I've posted it before, but here's a jpeg of a drawing I did that shows how to set up this style of clunk tank.