Richard,
the eligibility guys are very hard on any changes to brakes. I had mine checked at Winton as did all the Zs. One had cross drilled rotors and was told to get them off. Only the standard rotor and caliper are allowed. I've tried several brake pads and found little difference except initial bite. All the pads are destroyed at the end of the weekend, especially the outer pad nearest the wheel. The inner pad has some ventilation from a duct. The outer pad is almost impossible to duct.