Yes, complexity in simplicity.
Reversion is just from the very basic design of a 2 stroke. Just like when a piston rises in a cylinder, when the transfers and exhaust ports are covered by the piston, compression is created, when the piston starts down it is also trying to create compression in the crankcase. This pressure gets bled off through the intake port until the piston skirt covers it. This is reversion, as the flow through the intake system is reversed. What this does, and why it's bad, is, the less pressure/mixture in the crankcase, the less mixture pushed/pulled through the motor, IE less power. Add in, that a carb doesn't care which way the airflow is, when the air flow goes back through the carb, fuel is picked up. Which is called doubled Carburation, which makes jetting difficult, and also the turbulence of the flow having to reverse again to fill the crankcase on the piston up stroke. A piston port is just a very simple design, and reversion is a big drawback on that design. Yes, there are ways of reducing the effects of reversion as was posted, with intake length and area. And also by limiting intake port duration timing.As far as your manifold mod, I doubt you will be able to tell much, if any difference. The added area between the carb and reed, in theory, would decrease the pressure on the reed when closed as there is more area for mixture to compress into. But it is so minute, it should not be a big deal.
