Cross drilling is a factor in cooling in race applications to prevent fade and also in the wet as it reduces the time the brake pad floats on the water film as the water film is dispersed not only outward but also into the holes. In race applications or on a motorcycle it is a big deal. On a street car it is so-so and mostly for boy racer looks. Many modern street Ferraris and Porsches did NOT have drilled or slotted rotors. It is often a waste of money with poor results. Fred 6894 since new; now in Houston for Stages 1 and 2; 9,000 miles [Non-text portions of this message have been removed]