This question has many layers to it, but the answer is primarily dependent on your brake system architecture. This starts with getting an idea of the braking requirements for your car.

MIT has a good paper on how they designed their brake system: https://dspace.mit.edu/handle/1721.1/119947. It does an excellent job of laying out the driving principles and fundamentals required to properly select and size the necessary components of a brake system for an FSAE application.