Just in case the picture isn't clear, here are pics of each pad. #1 is the one that cracked completely in two.
Originally Posted by xerox445
I am a little confused. Are the pictures you have posted (OP), of pads from a stoptech big brake kit on your car after a HPDE with Kumoh XS's?
Just looked at your video. Everything seems fine, and there is so much time inbetween those big braking zones there should be no issues. More so, with the big brake kit, which is increasing rotor mass, and braking torque; to do that kind of dammage to the pads, you would be overwelming the tires well before your brakes gave out.
I have the XS's on my car for street tires, and theres no way they have coeficent of friction to cause an issue like that, unless you were really romping the crap out of the car. After just watching your video, your driving great, I agree with your instructor %100!. Even if you were on R-comps I still don't think its that likley.
From the looks of those pads, you have a piston in that kit thats seized, or the pad was not floating freely and cocked on a pin or slide. Look at the wear on the bottom pad in your picture! What do the rotors look like?