What is better: drilled or slotted rotors?
Power Stop makes cross-drilled only and slotted only rotors (in addition to a cross-drilled & slotted combo). There are distinct advantages to each.
Brake rotors can exceed 1000°F where many friction compounds start to break down. The high temperature can also lead to annoying brake pulsation and a shaking steering wheel.
Drilled rotors are engineered to keep your brakes cool, so your brake pad has improved pad bite with reduced fade. Drilled rotors can operate up to 200°F cooler to protect against rotor warping. This is why some high-end vehicles (such as Corvette, Porsche & Ferrari) come equipped with drilled rotors.
While a slotted rotor does a good job of removing gas and dust generated by the friction pad, it does not cool your brakes.
Improvement in brake output from drilled rotors is the subject of SAE Technical Paper 2006-01-0691 "The Effect of Rotor Crossdrilling on Brake Performance." In a nutshell, for street and highway driving, drilled rotors are typically preferred. For track, autocross, towing or other severe-duty applications, slotted rotors are recommended.
For more details on the advantages of each rotor style, visit Power Stop Research.