Advancing/ Retarding Camshaft

Just wondering what the benefits or disadvantages are in advancing or retarding Camshaft. I am going to be swapping out the camshaft /lifters and was wondering if this would be beneficial for more lower end. mid range torque. The bushings I am looking at are in degrees of 0,2,4,6,8. Any assistance on this is most helpful. Comp Cam Camshaft, Hydraulic Flat Tappet, Advertised Duration 272/272, Lift .454/.454,