I'm guessing they get a better margin on the AA kit.
Also, I'd consider the Turner track pipes over the AA HFC X-pipe since the most important area to open up on the X-pipe where the primary cats are. You'll save more than $1,000 too.
Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."