I have shimano M446 brake with rt-56 disc. Normally they work pretty well but on longer descend, as the heat build up, the brake lose its power. I think change the rotor and/or the pad would help solve this problem. Is there any more fade-resistance rotor and pad on the market?

My hub is the six bolts type, and my fork, Rockshox XC28, can only take 160mm rotor at maximum.