upgrade master brake cylinder

Has anyone with a factory '70 A body manual disc car installed the MC5621 and if so how much more pedal effort in your opinion?

Also does anyone who replaced their manual disc master with the DoctorDiff have some pics of the finished install?

An 1-1/8" master will be a significant increase in pedal effort. That's even larger than the factory manual master cylinders which are 1-1/32". To me, even the 1-1/32" stock manual master results in a pretty hard pedal. Changing the stock master out for a 15/16" changes the pedal effort dramatically, although it does increase the amount of travel needed. The smaller bore results in a higher brake line pressure and a longer pedal stroke. The larger bore reduces line pressure and reduces the pedal stroke, but that means all the force has to be applied over a short pedal distance, which gives the high effort. There's no way I'd run a master cylinder bore that was larger than the factory 1-1/32" with the factory brakes, that will make the effort even higher and I already swap the stockers for 15/16" on all my cars.

Here's a picture of the DoctorDiff master cylinder in my Duster. The hydraulic clutch master cylinder is to the right of it and my adjustable prop valve is below it.
IMG_6565.jpeg