Direct from Carbotech FAQ section:
If you have had another manufacturers brake pads on those same rotors; then you will ABSOLUTELY have to replace or resurface (turn) those rotors before installing the Carbotech brake pads.

If the rotors and drums are in relatively good condition, meaning they are smooth, flat, with no visible cracks, deep scoring, distorted, and with no other visible damage; and you have ONLY had Carbotech brake pads on them, then they do not have to be resurfaced or replaced.

Carbotech XP16
The second compound to be released this year from Carbotech. It is a step up from the highly successful XP12 compound. The XP16 leads the highly touted XP series line of compounds from Carbotech. With an extremely, and we mean extremely high initial bite, torque and fade resistance than compound XP12. XP16 is a world leading friction compound that is unmatched as a Ceramic racing compound, with a temperature range of 250°F to 2000°F+. Carbotech XP16 still has outstanding release and modulation that has made all other Carbotech compounds so successful. The XP16 is the most rotor aggressive compound Carbotech makes, but compared to it's competition the XP16 is still very rotor friendly and contains 100% non-corrosive dust. XP16 is recommended only for expert/very advanced drivers. XP16 is found to be most affective on race cars weighing 3,000lbs or more using R-Compound tires only. Ideal for sprint use only in classes such as T1, T2, H1, GT1, GT2, GT3, GT, GS, DP, P1, P2, etc... Not recommended for use as a daily driven street pad due to possible elevated levels of dust and noise.

Available Options:
Option:	nonePre-bedded pads ($20.00)
This product was added to our catalog on Friday 06 August, 2010.
Customers who bought this product also purchased Carbotech XP20 GT-R Front Brake Pads Carbotech 1521 Bobcat GT-R Front Brake Pads AMSZ Max Slot Rotors Disc ONLY, Rear Pair AMSZ Max Slot Rotors Disc ONLY, Front pair Carbotech XP12 GT-R Front Brake Pads