OK, for high speed woork that's going to take some effort.
For the big bux, step up to a full brake upgrade, like Wilwood or Bear. Lots of bux, but durable and reliable lap after lap. I'm pretty happy with my Wilwood system.
One of the great tricks to good brakes is keeping them cool. That's probably why feel slippery towards the end of the day. Considering adding brake ducts.
DO NOT get drilled rotors. You will lose braking effectiveness, and need to replace the rotors pretty often.
Here's some pictures of my Wilwood upgrade, from stock Fox body brakes:
bobcowan/Wilwood Brakes - Photobucket - Video and Image Hosting Pretty remarkable improvement. Allows me to brake at the 1.5 marker, instead of the 3. Sometimes they work so well that I slow down too soon and too much.