First off, Big Kudos go to Gary Donovan for 90% of my build. He is a great friend and mentor.
Traction and stabilization. Traction for fwd cars, the more weight on the front tires the better. With that being said you also do not want the rear end sky high for stability reasons. Also when launching and shifting you will lose some power, traction, and some time when the rear end squats. I can also control how much weight i want on each tire depending on how the car hooks up at different tracks and lanes. If you have ever raced, you know how frustrating this can be. And yes I have a portable scale Proform 67650.
Gary Donovan has a great write up on his website.
http://www.thedodgegarage.com/traction.html
If you look at this video you will see exactly what I mean, this run was with airshocks only, notice the squat and bounce
https://www.youtube.com/watch?v=xh5Gw7K0ufo
This run is when I installed the lock down. A lot less movement.
https://www.youtube.com/watch?v=x6biRH8iRr4