Matt is correct here, 90% of these "cross drilled and slotted" rotors are weakened due to les material, I didnt say they dont work but they certainly will not last long with considerable braking force.
I had a set, they sucked, warped after one track, and I honestly could tell zero difference between blanks and the cross drilled and slotted rotors i had on, there was no extra heat dissapation, the brake fade happened in relativly the same amount of time with both rotors.