Yes, the C5 has larger rotors, without any brake bias valve it will throw the brake bias off also. Very dangerous. They are also designed to operate @ a higher line pressure. The C5 master is 1" bore diameter, the C3 power brake one is 1&1/8? The non power is also 1". Why not include a C5 master, it's a bolt on replacement. All you need is the lines to go from the M12x1,5 & M12x1 master sizes to the un flare sizes on the distribution block.