Scott, that's a highly subjective question. All this stuff costs money. So if you are going to mod the bike, you should put your hard earned dollars where you want it most. Performance. Bling. Brakes. Looks. Motor. Handling. Long-distance travel. Paint. Comfort, & on it goes....
Sprockets riders generally work with different teeth to change either the power off the line, or possibly better gas mileage for distance touring. You'll see the name SuperSprox a lot on this forum, as many us have them. Busa is a high-horsepower high-torque bike so it has some special needs compared to others.
Braking mods are also highly subjective. If you are causal Saturday rider, possibly stock brakes are just fine. Your Busa comes with rubber brake lines though, and a 550lb 170 hp bike, rubber lines are not advisable. But again, depends on ride style. Even region perhaps.
Here in California - there are mountains in every direction I go. All super-twisty. I need excellent brakes.
So put the money were it makes the most sense for you personally.