thats not a bad idea on your brake lines dh, i know someone with a similar setup on a fwd and he has to run 2 bias valves to get the right bias
I had to ask a lot of questions on a lot of forums before StephCassCar just happened to swing by Bristol for a cuppa and we talked through how best to do it.
Seems to work well enough for me. Obviously the big risk is (where the MC has two 'compartments') if one front brake goes, so does the other.
I'd like to think on a track car, which gets *quite* a lot of love and attention this is a pretty unlikely situation!
I've run the rear line through the firewall and down the side of the tunnel, inside the car. It then goes to the bias valve, which is mounted on the rear seat base, through the boot floor and tees to the rear calipers on top of the rear subframe - bit different from the boot floor onwards to what you'd do on a 2WD.
Remember for an MOT it should not be possible to reach the bias valve from the driver's seat.