Not likely to see much benefit if your Z is a DD.
Under track conditions, the repeated brake temps will continue to increase, thereby increasing the brake fluid temps that evenually will find it way to the weakest line in the brake system. At that point, when you need the brake to work flawlessly, the brake pedal will, at best feel mushy, or at worst, the brake pedal will simply bottom out and one will not be able to stop!
BBK are great safety peace of mind, even for DD conditions. You will likely not see a significant decrease in stopping distance but brake fade should be reduced. A benefit of two-piece rotors is reduction on unsprung weight. Also, chaning from DOT 3 brake fluid to DOT 4 will lessen the when the brake fluid boiling point.
Additionally, the brake booster should be sized appropriately to take advantage of the BBK.
