I'd have to look at my data, but I seem to recall seeing higher peak numbers. There's quite a bit of skill to braking.

Adjustable prop valves make it possible to get the fronts really working at their max if you are locking your rears. I actually adjust my prop valve a couple times a lap at certain tracks due to braking areas that are hilly. Some guys run TWO adjustable prop valves, one for each rear wheel.