brakes and replacement

i want to replace the rear axle or something to get rear disk into my 97 sentra. mainly i want more power to go to the rear wheels instead of most going to the front. does anyone know what rear axle i could replace the back with that will have a disk and be compatible to the rear with minor adjustment? also i heard there is some sort of limiter on the rear brakes which makes for a decrease in the amount of power going to the rear. does anyone know if this is true and how to get rid of it?