[74proii]

It's not he booster that's the issue other that mounting depths, bolt patterns and actuation rods. They all just multiply force by using the vacuum to aid in actuating the booster, e.g. less force required to move the master cylinders internal piston. Master cylinders have different internal diameters which produce the force. Larger the diameter, the more force applied, basic fluid dynamics. Outlet ports vary in size, a few differ i diameter. There is nothing wrong with drum brakes, they actually hold better that disc. Where the disc brakes are better is in the front, because if you do not adjust front drums correctly you will dive to either side based on how they were adjusted. That is why heavy duty brakes,for heaver vehicles like station wagons use drum rears. Look at 2.5 ton military trucks, drum brakes to prove the point. Discs are easier to service, and have newer compound that hold up to heat better, thus less brake fade.