Pad Deposits from Z Rated
Personally, I would not use Z-Rated PFC's at the track. I know some have with success, but my experience was not positive. I had used them for moderate track duty on a C5 Corvette without issue, but the M was a different story.
These deposits were after 2 days at WGI. They stopped just fine, but with a very definative "GRRRRRR" on the track.
On the way home, the rotors were simply unbearable with the vibration. After 300+ miles, I was ready to hone them to see if they could be saved. On the advice of a friend I switched back to the stock pads do the clean up work - it took nearly 750 miles to remove the deposits and return the rotors to normal.