i didn't specifically ask that question, but my impression is that the hp increases are what the mufflers by themselves will bring to the table with a proper tune, anything that an upgrade in header pipes will do would be added to that. Again, my impression .... could be wrong, but I doubt it! 
Hey Dennis
Your Ultra has 3 large air flow restrictions. The stock air filter is the easiest to remedy and test. In the dyno room, removing the stock AC and testing with an open TB is an instant 5 hp gain on a stock CVO Ultra. Replacing it with a typical Stage I HD or Ness drops you back 2 HP. In other words, replacing the AC with a Stage I nets you a 3 HP gain.
Next: The stock cat headpipe and mufflers are both very restrictive. Replacing one with out the other will only show a 2 HP gain. Thats right, mufflers only, 2HP gain and that's it. Removing the cat from the stock headpipe combined with 2.0 cores will show a solid 8 HP gain. Step up to an XPipe and see another 4 HP. Remapping is required to support any substantial power gain. With the right combination of intake and exhaust bolt ons and a little computer work, 12-15 hp gains are common.
The dyno chart belongs to CVO Member Gail fields. 2010 CVO ultra, Stock VS Stage I XPipe Sleeper kit. Same day, same tank of gas. Gail had one of the strongest baselines I have ever seen at 102 TQ off the showroom floor.
Gail almost wheelied the whole block when he left!.
Steve George
Fullsac Performance