In reply to jimbbski :
You wouldn't encounter this kind of problem in a race.
You get it after driving a long time at speed without touching the brakes. Ten minutes, twenty minutes. On my B12 there was one trip I took where I would literally drive for almost three hours without needing to touch the brakes. The pads are cold, the rotors are cold, everything is wet because it's not hot enough to boil it off as soon as it touches.
Then you apply the brakes, and the best way to describe it is that it feels like the pads are hydroplaning. They aren't generating enough friction to make enough heat to boil the water off so they can generate friction.
I can see how slotted or (gack) drilled rotors could help. The real issue, however, is pad compound.
what rotors did you use? When I upgraded to 330 brakes on my old 318ti, I also went with the ATE discs with the star pattern slots. Worst rotors ever for use in rain. Worked great in the dry, but, like you, the first second or two in the rain while on the highway.. nothing. Yes, I had dust shields, but those slots captured water somehow
Alfaromeoguy said:
But on the track you are on and off your brakes,often. I was on the freeway for 20 mins, no brake action. Might be a different situations.
you know it's funny I have very few freeway miles under my belt but throttle modulation has always been the most comfortable way for me to drive however it seems most drivers prefer to tap/ride the brakes so I do occasionally have to use them. Most of my miles used to be in old neighborhoods and I still only had to use the brakes other than the engine because of clueless/professional drivers of which there were legion.
It does come down to the theory or is it fact that it's not the brakes that stop the car it's the tires.
I would in a very uneducated way say go back to oem and put more expensive tires on even though I can't afford expensive tires. 
