We present simple scaling rules to optimize the design of 2R optical regenerators relying on Self-Phase Modulation in the normal dispersion regime and associated offset spectral filtering. A global design map is derived which relates both the physical parameters of the regenerator and the properties of the incoming signal to the regeneration performance. The operational conditions for optimum noise rejection are identified using this map and a detailed analysis of the system behavior under these conditions presented. Finally, we demonstrate application of the general design map to the design of a regenerator for a specific 160 Gb/s system.