Pinion angle is the angle between the driveshaft and the rear axle. The pinion is the gear at the end of the driveshaft that meshes with the ring gear on the rear axle. The pinion angle is important because it affects how much power is transferred from the driveshaft to the rear wheels. If the pinion angle is too high, then there will be too much friction between the driveshaft and the rear axle, and not enough power will be transferred to the wheels. On the other hand, if the pinion angle is too low, then there will be too much slippage between the driveshaft andthe rear axle, and again not enough power will be transferred tothe wheels.
The ideal pinion angle depends on a number of factors, including tire size, vehicle weight, suspension type (live or independent), and driving style. For example, a drag racer would want a very different pinion angle than someone who does mostly off-road driving.
CalTracs are devices that are installed between a vehicle's frame and leaf springs (on either side) in order to change its static (non-moving) position. This changes where your car's center of gravity is located which can help with traction issues - giving your tires more grip on slippery surfaces like when you're accelerating hard out of turns on a race track or pulling away from a stop light on a rainy day.
CalTracs can also help adjust your car's ride height which alters its aerodynamic properties; lowering your car can make it more stable at high speeds while raising it up can give you better clearance over obstacles when off-roading without sacrificing stability too much. And finally, CalTracs allow you to fine tune how stiff or soft you want your car's suspension to be which can come in handy depending on what kind of surface you're driving on (smooth vs bumpy roads) or even just personal preference.