As it has been pointed out in previous posts.
One major improvement is to step up to the stainless hoses for the front calipers.. Your originals swell up under pressure and gradually swell more than they did when the car was new. Gradualism is the term since it happens gradually most drivers won't notice it.
Brake proportioning valve I have covered this before in my weekly inner circle. Since I have a collection of GM books etc turns our GM used 3 different suppliers for the brake proportioning valve in these cars. Only one version was brass. Brass as you know don't rust. Those of you that may not know where this valve is located it is under the car by the floor pan like where you would rest your left foot. The perfect area to corrode year round.
Perhaps the biggest shortcoming owners where not told to do was to flush the brake fluid every 1-2 years to keep it clean. Small particules of dirt can wreck havoc in the powermaster system. clogs check valves etc.
More mistakes is overfilling the reservoir the left bank (passenger side) should only be about 1/3 filled while driver side should be like 2/3 filled when everything is flushed and bled properly.
GE made a few errors early one black brake switch safety recall would leak brake fluid grey switch is correct switch can blow fuse don't ask me how but it can. Original brake bowl was all black with nut inward by unit. Second design had the yellow silk screen wording and 17mm nut on exterior. Latest design of course is the reproduction Cardone bowl which is probably 15% larger than the original bowls and nut is inward. Those bowls have had zero defects. Afterall they are 25 plus years newer so advancements have been made during those years.
Recent brutal winters ad other problems even in late model cars with brake lines rusting through. (I had it happen on two cars)
Granted because of a multitude of screw ups the powermaster has fallen out of favor with a good portion of owners it still is the method to stay with if you want to keep your car as original as possible. We sell both rebuilt and new vacuum set ups and rebuilt powermasters.
So options exist......
denniskirban@yahoo.com
I can tell you from firs hand experience replacing the stock rubber brake hoses to front calipers makes an immediate difference you will be able to feel.
We sell that kit as do others think it includes a 3rd stainless hose for the part that goes over the rear. I have the kit on my personal car which still has the powermaster on it but I did have the bowl replaced last year and fluid flushed. Fluid should be almost clear and not look like Pepsi.
My car has 80,000 miles on it but not driven much in the last 2-3 years.