I think you mean a step bore master cylunder, as in the bore steps down in diameter for the forward piston.

The logic is fundamentally sound considering the traditional process is to essentially push on the brake pedal. This device speeds things up. Go for it!

I don't know if Erzibleed works with the pressure ABS requires. Might as well go with a Motive.

Sixto
83 300SD
98 E320 wagon