I'd like to see a 4-pot on the back rotors though. I would put them on for track duty. I think most road racing guys would agree that going with a 6-pot front/4-pot rear would be more than enough.

 

Again, bling. The FR500S, FR500C, and BOSS302Rs all use the stock rear calipers w/ upgraded pads. The 4-pots look cooler, but you don't need em.

 

You can't say that a larger caliper with more surface area and clamping force is purely bling. You also have to remember that they haven't opted to make a production 6-pot caliper yet. Also, some of the Grand-Am & AI cars i've seen have some 6-pot Brembos up front. The difference might be marginal, but they do offer some improvement.

 

It's all about brake balance. The 4-pots can lock up my race tires with a good set of pads at 70mph, they've got enough clamping force. It would be interesting to see what that option would cost, too. Aftermarket 6-piston kits are about $3500. Then you get to pay for more expensive pads and rotors as well.

They could be cool, but don't necessarily take it as a "more is better" thing.

 

Increasing rotor size isn't really bling, but it adds cost. Look at all the high end cars and notice what size rotors they are wearing.

 

Giganto! Our 335 has some super meaty rotors, then take a look at the M series, the calipers are nothing special but the rotors are bigger and drilled. I think the Brembo 4 pots can hold their own, now keep on bringing the large rotors and more pad surface area. I would like to see them match the fronts with a 2 pot rear caliper just because it looks weird with the Brembo fronts. Look at the Nissan Z/Infiniti G brakes, they are doing quite a bit with a 2 pot rear caliper and a lot of pad. Plus it looks better with the 4 pot front brakes, maybe even do what they did and put Mustang across the brakes. Or nothing at all. I'd take the GT logo.

 

Just to update this, the rotors I had heard about were in fact the 2013 GT500 rotors and calipers.

 

"Stronger" brakes aren't really the issue, any brakes that can lock up your tires are by definition strong enough. The question is brakes that can keep on stopping, again and again, and that's where the bigger, fancier brakes are beneficial, with all that size and fanciness basically going towards dissipating heat, not in applying any more initial clamping power. That and perhaps a bit better feel through less flexible hoses and calipers. Front brakes on front engined cars do probably 80% of the actual braking due to the weight shifting forward whereas the rear brakes are almost along for the ride. Thus, beyond a certain point, making the rear brakes too big and fancy quickly become a waste of mass and money in all but the very Nth degree of racing (Le Mans might come to mind when slowing down from 200+mph at the end of the Mulsanne Straight for a day would tax most any breaking system).

 

Keep in mind that adding pistons doesn't equate to more clamping force. What adding pistons generally does is help spread clamping forces across the pad in a more even manor.

While it adds some feel and fine modulation to the pedal and helps with pad wear, it doesn't necessarily increase braking performance.

The rear brakes in these cars don't do a whole lot and as such, you don't need a ton of braking performance back there. Adding a 4 piston caliper in the rear wouldn't stop you any faster, but you might get some more feel from the pedal.

What the rear needs more than a better caliper is a bigger rotor to sink heat better. My on-track experience has shown that heat sink and dissipation of the rear system is the weak link in a Brembo equipped car.

Going to a larger rotor would help here. Fortunately the aftermarket has addressed this with caliper relocation brackets allowing the use of larger rotors.