They're post cat cut out's so you shouldn't need any tune for more power. Now if you put them pre-cat, then you may get some extra power with them. The Porsche guys like to put them in Pre-cats.
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."