Just be careful -- not all the OE and ACDelco rotors are FNC. They sell "standard" ones, "coated" ones (not FNC but it is hard to tell that), and "FNC" ones, both in GM OEM and ACDelco brands. The FNC ones are actually very hard to come by. The coated ones are still very good and will last long too just not as long as the FNC ones.
As a side note -- FNC rotors should NOT be turned down. Any shop that is doing that will definitely "smooth" the surface but they are actually removing the FNC (that's where the GM minimum thickness requirement comes in since it relates to the depth of the process into the steel surface). FNC is not a coating; it actually changes the metal properties to a certain depth in the rotor. After that layer is removed the rotors are basically just untreated steel and will warp/shred faster than even cheap auto store rotors.