Vandy 2 signature upgrade question

Need some far back can you go in the Vandy 2 line and still ship them to give them the "signature" treatment? Also, has anyone done this? What were the results?
While I am not an authority on this, you really should call Vandersteen to verify, the entire model 2 series is NOT upgradable. I had 2Ci's for about ten years and never came across any upgrade information. The Vandersteen website says nothing about it either. I aksed Richard Vandersteen about this a few years ago and I beleive his reasoning was economics, a $1300 speaker can't have that built into it, whereas the $2500 model 3 could (of course the 3A Sig is now $3500!).
They have to be 2Ce's. I know my 2Ce's are even too old. There was a cut off in the serial numbers of 2Ce's for the upgrade. It used to list the info on their web site. It is gone so I assume that they don't do the update now. You will have to make a call to your dealer to find out. I wouldn't call the factory!