1) Check The Size Of The Brake Pads And Caliper Width
The first and most important thing to consider is the size of the brake pads and brake calipers, whether you are getting them in a set or as individual items. The brake pads need to fit exactly the width of the caliper. Larger brake pads require larger brake calipers.
As a general guideline, if you are looking to upgrade the front to a 6 or 8 pot brake, then the rear should have a 4 pot setup. Similarly, a 4 pot setup at the front goes well with a 2 pot setup at the rear. Since most manufacturers supply only upgrades to one axle, it is best to upgrade the rear with high performance brake pads and rotors to balance out the braking force.
2) Ensure Width Of Rims Are Able To Clear The Larger Brakes
The second thing is to ensure that the width of the rims are able to clear the larger brakes by checking the dimensions of the disc rotors and brake calipers. If your rims are barely clearing the brakes, then wheel spacers can be used to increase the clearance. Also ensure that the brake rotors are able to fit your wheel pitch circle diameter (PCD)
For optimal braking performance, brake kits have to work in conjunction with good brake fluids and braided steel brake hoses and not forgetting a good set of tyres.