Is it possible to upgrade these units to include the WAAS option? Thanks!

Yes. All you have to do is get the Waas antenna. I would check with Lowrance, before I bought it. Their advise to me was that the accuracy was not as helpful as learning boat control. Just check with Lowrance.

I have an X16 and I updated mine to WAAS by changing the antenna to a WAAS antenna. For it to work you have to update the BIOS to the latest version on the Lowrance site. I believe the latest BIOS version is 2.7, but version 2.5 will work.