I think if you're gonna worry about the amount of sodium while injecting and or brining, don't do it! If the bird is "enhanced", maybe that's enough for some. Personally, I haven't looked at whether it's enhanced with an x% of solution the past two thanksgiving birds I've done, and brined them as I normally do and it turned out great. It's Thanksgiving, I'm too busy smokin' the bird, drinking beer and watching football to worry about sodium!
Aloha served daily!