my manual brake experience

I run the Dr diff manual brake master cylinder with an adjustable push rod. With the 4 wheel disc brakes it stops as well as my 06 Ford. It feels so much safer to drive now.

I put 200 miles on it yesterday, cruising the mountain roads, and it was so much nicer to drive. It was great having control on the twisty roads.

Just adding power assist may not resolve your brake issues. I would try to isolate a possible problem first. Maybe, as it's been said, it's just a matter of mismatched parts.