if they do its negligible. the main purpose of the SS lines is to deflect less when you pressurize the brake fluid then the stock rubber ones. this produces more resistance when you apply force to the pedal, since the SS lines move less, thus allowing the fluid to reach higher pressures sooner. thus it improves the "feel" of the brake pedal, but has no real effect on performance of the brake system. it can also decrease the risk of brake line failure from a rock or something along those lines. to reduce fade, you have to either increase heat tolerances of the brake components or increase the heat disappation rate. mods along these lines are cross-drilled/slotted rotors, larger rotors, higher performance pads, more calipers, ducting, higher performance brake fluid, etc. also, if you brake hard alot or if you ever fade the brakes, even just a little, make sure to bleed the fluid.