In this paper, we present computer simulation results of a phase-sensitive fiber optic parametric amplifier (PS-FOPA) in the so-called dual-pump degenerate configuration using highly non-linear fiber (HNLF) with the pump lasers' frequencies located symmetrically around the signal central frequency with 200 GHz offset. The main purpose of the study was the evaluation of PS-FOPA regeneration performance for differentially encoded binary phase-shift keying (DPSK) signals, taking into account pump laser power, signal distortion level, and HNLF chromatic dispersion. A relationship has been established between noisiness of the input signal and optimal power levels providing the lowest output signal bit error ratio. Higher noise levels require higher signal input power to reach the point of gain saturation. Chromatic dispersion coefficient of the HNLF has a substantial impact on the regenerator's performance. Positive values show a rapid drop-off in performance while negative values can allow greater signal quality improvement at the cost of higher input power.