theres lots of things that can effect it. cable actualy brake used pads boosters A booster always helps. Look into getting some non compressional cable outers, like bmx linear cables or nokon, that makes a huge difference. Brake calipers can flex, not much can be done about that other than buying new stiffer ones (avid ultimate). Soft pads can make a brake soft, which pads have you got? Getting some decent harder ones and a grind will make the brake stiffer. I have an avid ultimate setup with shimano 6mm gear cable outer 2 boosters and my own pads, its as stiff as any magura!