^This
Roll Center is not the same as the Center of Gravity, and can be adjusted independently (for the most part).
The closer the RC is to the COG, the less the chassis will roll in a corner. This will make the car react more quickly, as you're not waiting for the car to actually
roll before it starts changing direction. This lack of roll results in a car that will rotate more freely though a corner.
Lowering the inner ballstud height, e.b. shaving the rear brace on a B4, will raise the RC. This is an adjustment best suited for high traction, or tight, point-and-shoot style tracks.
I'm tired of typing, so raising the inner stud on a B4 will have the opposite effect. It will move the RC further away from the COG, resulting in increased chassis roll. This will tame down initial steering, but will put more weight on the outside wheels in the middle/exit of a corner.
For those that want to try it out, rear RC adjustments are more pronounced than front. Start off with no washers under the inner ballstud, reset your camber, and turn a few laps. You should notice more turn in, and more rotation though the corner (e.g. looser).
Now go back and add 2mm worth of spacers under the inner ballstud (this is a BIG change). You'll notice that now the car is more stable, and easier to drive, at least at RCHR.
http://users.telenet.be/elvo/3/3.html
^ lighter read than the "tune with camber links" thread.