to be engineered ur brakes only have to be able to handle the amount of extra weight that you put into your car/ute... not the amount of extra power.... although if you've got a quick car it'd be a good idea to have good brakes....
the theory is that as you can only do the speed limit (well supposed to) on pulblic roads...... your brakes must be good enough to stop the weight of your car from 100kph or whatever your highest limit is....
so basically a 400HP CA ute will get engineered with the same brakes as a 200HP CA ute... well in melbourne anyway...