Getting things out of balance is the major problem inthat factory brake bias is tough when you change anything: tires, pads much less major brake components.
Oem was near perfect in that they wore the pads amost equally at 22k +- 2k front and rear.................due to using the the rears more than most cars, they gained 3-5 even 10 feet compared to others of that era.
In a panic stop ABS [activation] just lengthens the stopping distances to preserve tires against flat spotting.
A simple panic stop from 60 will tell you by how many ABS activations you have how badly out of balance you have made the system................use an electronic counter to count the cycles and loacations rear vs front.
Every braked modded car I've driven was worse than just a perfect oem system...............in panic stopping cold or hot from 80. But I haven't driven them all!
Always good to review what they tried on 350z and the dismal results considering initial and future cost:
http://www.zeckhausen.com/testing_brakes.htm
Best was 4 feet improvement out of 200 feet at 80> zero