Bring on the Metal!!
Pinion angle will do nothing to help the car hook in a 4-link car, all your looking to accomplish with Pinion angle is what Power Mad said above. Pinion angle is the angle formed by the driveshaft and the pinion gear in the rearend. It is simply the angle at which the u-joint operates. IC on the other hand is what you adjust for traction and handling, and how to set it properly is something that requires knowing certain variables. I could tell you more but then i'd have to hunt you down and kill you..:-D