slots and drilled are for de-gassing/gassing off the layer of gas that forms on hard braking, between the pad and rotor. drilled are a poser mod and prone to stress cracks, slots are a better compromise. the GTS-R racers that one LeMans and Daytona had solid rotors. If you must mod them go with two-piece with alum hats to loose weight(unsprung) to improve suspension workings. otherwise like mentioned above stock are hard to beat. BTW use the search feature many previous threads on just this subject and some have pics of fractured/stress cracked drilled rotors