Nope. Stock 10.1's in the front... 10.5's in the rear. What other cars have larger discs in the rear, than the front? Pretty dumb IMO

 

Same reason lots of horsepower doesn't make you go fast.

 

Stopping my car from 130mph with stock brakes vs. my upgraded XG caliper/rotor combo was a night and day difference.

 

the slots and dimples help get gases made from heat out from between the rotor and pad...

thus helping the pad clamp harder, even if its just a little it makes what surface you are using for breaking more efficient+drops roational force

 

Larger rotors add more thermal mass, which allows them to absorb more heat before fading. They do not increase/decrease stopping distances appreciably.

More pistons to the calipers allows finer control, and in some cases can change brake pedal effort, making it easier(or harder) to get maximum braking without locking up the wheel.



The two together add thermal mass and allows finer control. they do NOT allow you to stop faster/better.



If you race/autocross, or drive aggressively, it's a worthwhile investment. If you've never experienced brake fade, you don't need them.



All that being said, people get them because 'everyone' has them, and they are an affordable upgrade so people can claim they did something to their car. Like most car mods, they are 75% appearance 25% function(If that).

 

If you're running very sticky tires (especially r-comps) you can overwhelm your stock brakes if you're pushing the limits of grip you can attain with these tires. So more potential grip means you'll generate more heat trying to stop quicker and take advantage of the larger rotors. Of course there's a practical limit, but larger than stock generally will help if you're running significantly better tires.