the 914 has more then enough brakes IF they work proper and the car is basically stock speeds! but hi speed big motor cars could use a little help. Mine are stock with slotted rotors and its all it really needs ....imo big brakes hold more heat and bite to hard !and what you do to the back you gotta do to the front
I do know of a few 914s that had them! AXing 1 locked up front inside wheel all the time and the other car was fast enough to warrant bigger brakes, both had same size hoosiers up front
JMO have fun