I don't know if you can do anything with this information, but I just learned something VERY cool about the VPX tank!
First I should tell WHY I did this. I love the VPX tank, but ultimately, I came back to the whole, "I don't like CE2's" thing... I have been thinking about a cartomator, but once again, I don't like cartomizers either. SOooo...I attempted this, and was very successful...
I took my VPX tank and put a normal atomizer in the tank. Very tight fit, but doable. Then I took my dremel with a cutting wheel, and VERY lightly began cutting into the side, just above the bottom cap. I made a hole, VERY tiny, just enough to see a light through. I noticed that the tube was too long, as the atomizer is slightly shorter, so I trimmed 1/8th inch off the end of the tube. After that, I put the tube back on, filled it, and popped the top cap back on.
The result, PLOOMS and PLOOMS of deep, flavorful vapor, just like dripping in an atty gives, and NO flooding. If you would like I can post a few pics of this.