Are you trying to eliminate a woofer in the footwell by improving the airflow/response of your door speakers?
I am trying to get some level of bass reproduction, yes... But more importantly I am trying to get a smooth response out of the door woofer. Without any sort of enclosure the woofer in the NSX door has an extremely erratic response in the midrange, and almost nothing lower down. The door is not flat. The speaker plates that we have to install on them do not work well at all. There are huge gaps between the plate and the door right next to the woofer. To create any sort of proper cavity you would have to Dynamat the crap out of the door. That adds a lot of weight, and it still does not give you very good response down low. Clearly an enclosure is best, and that is why the Bose system has one. The back half of this enclosure molds perfectly to the door. It creates an airtight seal and creates a decent baffle.
I have other woofers coming, that I am going to experiment with. These are smaller units that can fit where the Bose used to be, around 4 1/2 inches. They are high excursion, and also have a very wide frequency response. I am going to simply replace the Bose Woofer with some of these, remove the amplifier, install some more proper damping material inside the cabinet, and test to see how they sound within that enclosure, with the Bose port. I have one woofer in particular which should work very well. I am going to do sort of a head-to-head on all of these and see which design and which woofer sounds best.
The way everyone is just sticking 6.5 inch speakers in the doors right now, to me, is completely wrong. It just does not produce good results. Perhaps passable, but definitely not good.
I'm a big fan of aperiodic membrane systems. I never thought about trying it on a mid woofer though. Good job.
It should work just as well for a mid-bass driver, as it would for a subwoofer. It is really the only way to get a lot of airspace, while keeping the properties of an enclosure. I am experimenting with different thicknesses right now.
I am making my own membranes from roxul insulation, at different thicknesses.