Just being in HPDE I dont bring a lot compared to some of the real race boys, but here's what I bring:

Spare set of rotors front/rear
Pads front/rear
Brake fluid
Motor oil
Water for rad
spare set of tires, no spare wheels
air tank to fill tires
Tools
Tent
EZ up
camping stove
cooler filled with water/juice/reeses peanut butter cups