Nope many will argue that they are for looks more then anything. Some will say that brake dust and such will disperse quicker with the drilled and some say that the slotted will decrease the weight of the rotor but not by much. Get what you like to see thru the rims you have and your set.

 

my understanding is that they are designed to dissipate heat - I don't know which design is supposed to be better, maybe its just a looks thing?

 

from:http://www.stoptech.com/tech_info/wp...lections.shtml


DRILLED VS SLOTTED ROTORS

For many years most racing rotors were drilled. There were two reasons - the holes gave the "fireband" boundary layer of gasses and particulate matter someplace to go and the edges of the holes gave the pad a better "bite".

Unfortunately the drilled holes also reduced the thermal capacity of the discs and served as very effective "stress raisers" significantly decreasing disc life. Improvements in friction materials have pretty much made the drilled rotor a thing of the past in racing. Most racing rotors currently feature a series of tangential slots or channels that serve the same purpose without the attendant disadvantages.