2001-02 Factory Big Brakes Explained
In 2001-02 Miatas came from the Mazda factory in three "suspension" options. Normal (or Base), Sport, and Hard S. The Sport suspension upgraded the sway bars and other pieces, but the Hard S option added a larger brake package. (In 2003-05 all Miatas got these larger brakes, no options.) This information is to help you 2001-02 owners decide which brake option your Miata has so that you will order the correct parts!
If you are the Miata's original owner you probably already know if you have the larger Hard S option or not. However as cars are passed to new owners, with modifications or lack of records, you may need to look for a few clues to help you discover which brakes your Miata has. Most Miatas have a sticker on their passenger side doorjam that will list "HARD S" to show they came from the factory with the larger brakes. Another way to know is if the Miata came with the larger factory 16" wheels to accommodate those larger brakes.
But if your Miata no longer has factory wheels, or if the passenger door jam sticker is missing, or if a previous owner modified an otherwise "base" car to the larger factory brakes - the easiest and most foolproof way to know which brake package you have is to measure your existing rotors.
To further establish which brakes your Miata has, you can compare the brake pads against these pictures: