ummm, the rear brakes should lock up if you press on the pedal hard enough. as with any brake system, if workign properly, there should be a point of locking up the wheels and sliding them on the ground. if they are not, you need to rebuild the caliper. if they are staying locked up, you need to rebuild the caliper.
the 03+ hyd setup is a nice upgrade if you can get everything you need to upgrade to it.