Yeah, even the slightest rear raising or front lowering will alter caster, taking out a little. When you do this, you can correcdt it a little by buying offset bushings for the upper A arms. By making the rear bushing offest toward the frame and the front bushing offset toward the tire, you effectively move the upper ball joint toward the rear, regaining lost caster. This helps the wheels return to straight after a turn and have higher speed stability. Camber is the tilting of the wheel inward or outward from the cars centerline. Lowered VW's have ridiculous negative camber on the rear IRS suspensions, looking like the tires centerline would intersect about 10 feet above the car. Generally, when you cranks the torsion bars down to lower the front, you dont alter the caster too much, if at all making them a little more negative. This will actually help steering but will wear out tires faster.