Any muffler shop can do it. HJC have been mentioned as good cats to ask for. Put some 200 cpi cats in the secondary position for more power. You'll need 300cpi in the primary position for no check engine lights... but then, what's the point.
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."