Kawasaki's have had notoriously second rate brakes, that is when compared to Hondas. The reality is that when you do as David suggest Kawi brakes are good, and the newer stuff with the "Honda" routed brake hose and a stainless line make them real good. if you still feel like you don't have enough braking you could go with a oversized rotor, different material brake pads, of course the pads come with a price, shorter life, more wear on your rotor. one thing that is often overlooked is the disc itself, if it gets glazed the brakes don't work as well.
I guess the other question I would ask, do you need more brake? My son used to complain about brakes and the calipers were cool, so he obviously wasn't using what he had. After a moto the front and rear calipers should be hot, if your getting into corners carrying alot of speed they will be hot hot.