From fiddling around in hornresp I think a smallish inner port area is often required to create good efficiency, response, and displacement predictions. I have theorized that inner port loading and how it interacts with the other chamber is very important. It will be interesting to see the findings of the experiment. Your other thread on series 6th's was loaded with practical info, thank you for testing the theory.
I myself have a series 6th in the works for a first gen alpine type-r that I have laying around, might be some time till I can actually get to box building, have made some good designs, though.