Smoking Crater, I was not referring to you but rather Nigel Fraser Ker, the "expert" who went to so much trouble to prepare the website mentioned by Rusirious. I think it is one thing to hold an opinion and another to get on a high horse and act like a big expert with a special website.
The pressure from the exhaust is determined by the engine and exhaust system and will be exactly the same, regardless of where the tube ends up in the tank.
There is no difference in pressure between a normal tank and the "uniflow" tank, except for clunk problems, bubbling in the fuel right at the carburator clunk intake and backflow problems.
Allan