Just like the earlier generations, the new MX-5 uses disc brakes front and rear. There were two sizes of brakes used and all cars had ventilated front and solid rear discs. Generally speaking 2.0 cars have the larger brakes and 1.5 cars have the smaller.
1.5 litre engine cars have 258mm front disc and 255mm rear disc
2.0 litre engine cars have 280mm front disc and 280mm rear disc
The exceptions to the above are the Japanese market's RS and NR-A models. These cars used 1.5 engines but were fitted with the larger 280mm brakes for extra stopping power and to position them above the lower specification cars. This means it's likely 1.5 cars can be easily upgraded to use the larger brakes, as was the case with previous generation models.
As well as the usual Anti-Lock Braking System (ABS) and Electronic Brake-force Distribution (EBD), The ND model has some updated safety features built into the braking system:
Brake Assist
"During emergency braking situations when it is necessary to depress the brake pedal with greater force, the brake assist system provides braking assistance, thus enhancing braking performance. When the brake pedal is depressed hard or depressed more quickly, the brakes apply more firmly.
When the brake pedal is depressed hard or depressed more quickly, the pedal will feel softer but the brakes will apply more firmly... a motor/pump operation noise may be heard. This is a normal effect of the brake assist operation and does not indicate a malfunction.
The brake assist equipment does not supersede the functionality of the vehicle's main braking system."
Hill Launch Assist (HLA)
This is an active safety feature included as standard on all models. The Hill Launch system detects when the car has stopped on an incline and keeps the brake pressure on momentarily. This helps stop the car rolling backwards allowing drivers to easily perform a smooth hill start with minimal effort.
Mazda offered a Brembo 4-piston front caliper upgrade for some models. This was normally red with white branding, but was changed to black with blue branding for the 990S edition.
Aftermarket Upgrades
Mazda's shop options catalogue gives buyers in Japan the option of painted brake calipers for a nice cosmetic upgrade. These were available in red, gold, or blue and look quite smart compared to the standard parts.
For a performance upgrade there are several aftermarket options available. The first step would be to simply change the standard Mazda brake pads to an uprated performance pad. There are too many options to list here but they will each have different characteristics, some will grip harder from cold, others will resist fade at high temperatures, produce less dust, or simply just last longer, your choice will depend on how you use the car and what your budget can stretch to.
If a pad change is not sufficient, you could also look at uprated brake fluid and stainless brake lines that don't expand under heavy braking, these will give you better braking feel and confidence. Upgraded brake lines are available from Knight Sports, Maruha Motors, AutoExe, Swage Line, Acre, and Endless to name just a few.
Mazda used a DOT-3 brake fluid and recommend you change it out every two years. The standard discs can be replaced with drilled, grooved, and slotted varieties. Aftermarket discs are also available with anti-rust coatings for improved looks and durability, remember nothing looks worse behind a nice set of alloys than rusty brakes.
Probably the best upgrade you can do with the MX-5 brakes is to replace the standard calipers for lighter multi-piston parts. These are usually made from aluminium and are available from a variety of manufacturers and in different colours. There's a triple benefit to upgrading the calipers, firstly they look good, secondly they provide a big improvement to braking performance, and thirdly they often weigh less than the standard calipers and less weight is always good.
Upgraded calipers may seem expensive initially but they really are worth it from a safety, style, and handling point of view. 6-piston calipers are probably overkill for road use, I think a small 4-piston upgrade that fits with the standard brake disc would be ideal.
Fortunately, such kits exist and below are some examples:
Flyin' Miata's Little Big Brake conversion uses Wilwood Powerlite 4-piston calipers with stock discs
Goodwin Racing's big brake kit uses Wilwood Dynapro 6-piston calipers with 12.88" Wilwood discs
Mazda's own Brembo 4-piston front brake upgrade as seen on the USA's Club model
Deck's kit uses AP Racing 4-piston calipers with 300mm two-piece discs
Original Runduce do a 4-piston kit with 286mm disc or 6-piston with 304mm disc
Acre's big brake kit uses Brembo F360 calipers with a two-piece 300mm disc
Endless have a kit for the ND using their 4-pot caliper with a 294mm disc
Knight Sports' kit uses a 4-pot caliper with 304mm two-piece disc
T-Demand offer two sizes of brake upgrade. A choice of 4 or 6-pot calipers are available in a wide range of anodized colours.