Camber gain.
One of the most powerful adjustments in a car, it really makes or breaks a car's handling.

The common misconception of longer upper link=more grip is somewhat true, depending of what the driver is trying to achieve the car has more "traction". Let me explain, camber gain affect mainly overall response. If a car has long upper links the car is lazier and is very controllable, also my experience shows that it can be aggressive because the rear doesn't bite well. On the other hand a car with short upper links is more nimble and bites the track harder.
I also tune the length relative to amount of grip available, the more grip the track offers the longer the upper link because there's a point where short links become too twitchy to drive and I go for a step longer.
Like racing on astro, if you use short links the car would traction roll every time you sneezed on the steering wheel or long links on a low traction dirt track, the car would feel like it's dragging a boat anchor.
Now I can't find where I saw a how-to draw camber gain throughout suspension travel but the rule of thumb is to have camber gain on compression and camber loss on extension, achieved with lower inner link position or higher outer position. Also since I had the rear shock piston breakthrough I tend to gravitate towards the outer hole in the inner upper link position(works really well in the TLR22).