My apologies for a post that doesn't answer your question.
A website a visited in the last week or so had a sale on Porsche carbon disk rotors. $9800 for a pair. Also, these rotors were for a two piece assembly...what looked like an aluminum "hat" to bolt to the spindle and then the rotor assembly to be bolted to the hat.
I think I may have saw that the C7 has a carbon brake option.