All great comments and after posting this, I've looked into three different CVO's of local folks in the Knoxville, TN area. The stock 2010 SESG I viewed has a core that is different than the one in my 2012 FLHXSE3. Funny, however, that the two other bikes were both 2011's (SERG and SESG) and both were stock (at least so far...) and one had the internals similar to the 2010. The other one (and yep, I checked...it was made closer to the end of the 2011 model year) looked just like mine. Looks like the motor company made a mid-cycle change sometime in 2011 to the current muffler configuration.
I've looked at three new 2012 CVO's (Ultra and two Road Glides) and they all had the same config as my CVO so please review/look at your muffler before starting this (or any) project as some of the details for modifications on a thread may not match what is staring you in the face.
As for the ECM, yes, they are designed for modest modifications without any changes to the programing. This would be a modest mod.
Some follow-up from the last bike I worked on using this procedure. At first he was hoping for a bit louder result. However, when he was riding behind mine last weekend, he noted just how much better it sounded. As he was use to a V&H system on his wide glide where the exhaust was right under his right ear, he realized all the sound on his SERG was way behind him. He was pleased after hearing and riding behind another bike. Again, no money out of pocket for this mod. It's not for everyone but it's a very inexpensive way to make a modest noise change. If not loud enough, there are plenty of vendors out there ready to take your money. My opinion and the route I would go if I were to make any addition mods were to go with the Fullsac system. I like the idea of looking stock but not sounding that way. Thanks for all the great comments