I drilled the two vent holes into the neck of the 510~eGo adapter, (the one with the fine cone threads) put the inside pieces back into the adapter backwards as discussed earlier, put an O-Ring on an unmodified steel CE2 for testing, screwed it onto the adapter, then screwed that on to my ProVari, the CE2 fires but no air flow.
I then messed around with the 510~eGo adapter bushing for a while and got air flow. The only way I was able to get air flow is by removing the bushing(s) from the side that has the two air holes drilled in the neck. I kept the bushing on the center piece for the other side. The CE2 fires this way and I get what seems to be a good air draw off of the CE2. Screwing the center pieces together or apart serves no function and you would not be able to adjust air flow this way. If you screw the two pins (center pieces) in the adapter together too far it will not fire the CE2 because it is not making contact with the battery. This draw seems right for me; the two holes I drilled are 180 degrees apart (I drilled one hole straight through both sides). You could drill four holes 90 degrees apart to get more air flow that would most likely be, IMHO close to how the original MAP tank draw is. NOTE: I did the air flow test through the unmodified steel CE2 without any juice in it, I feel the air flow would be the same with or without juice. However, I did miss out on a good hit of nicotine that would have been nice at that moment.

Modified 510~eGo adapter with O-Ring and a Black (steel) XL CE2, and it works.

510~eGo adapter.

Picture of other adapters for reference.
Next step is to get this modified 510~eGo adapter into the bottom delrin cap of the MAP tank.
PK