bias (front/rear balance) of the braking system? Because different tracks and track conditions can be fine-tuned for optimum lap times. As an example, during wet track days you will
want to increase the percentage of rear brake biasing a bit."
Well, playing with biasing is generally not a good idea, even for experienced racers. It's all too easy to overbias the rears, which will quickly lead to a spin. The front does 60-80% of the work in most cars, (except maybe those with more rear weight bias, e.g. 911, NSX, etc.) and adding more rear bias isn't necessarily going to help in general. In an iffy situation, it will/may result in rear lockup sooner, which you never want. It's also too easy to mis-adjust it on the fly, I know people who have spun/crashed/gone off because of this, and they were fairly high-level racers that knew what they were doing, just happened to hit the lever or knob at the wrong time.
Anyway, good info in the above post! (time to Track your car soon, methinks. ;-)
-Ed