Resonators are at the bottom. 200cpi cats in the middle (gutted here), and 400cpi cats up top by the O2 sensors. That's why he showed the clean welds just above the secondary cats where they cut it open to gut.
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."