This paper provides a comprehensive overview of the electricity supply situation in Nigeria, focusing specifically on enhancing the performance of industrial gas turbines, GE GT13E2 (Afam Power Plant owned by FIPL) in Port Harcourt. The study encompasses two primary aspects. Firstly, it involves an examination of the nominal operating conditions of a combined cycle system and explores their dynamic performance through advanced simulations. Secondly, the research introduces a supplementary burner into the combined system and conducts a comparative analysis, considering factors such as system efficiency and power output. The power plant configurations are simulated using Gasturb14. The analysis is carried out by establishing the maximum attainable temperature in the Heat Recovery Steam Generator (HRSG), which determines the number of stages of supplementary firing that can be implemented. The results presented in this paper unveil the substantial potential for power generation with the addition of supplementary burners, indicating a remarkable increase in power output, yielding approximately 187.444 MW. However, this significant boost in power generation comes with an associated trade-off, wherein the overall system efficiency experiences a reduction. From an economic perspective, the additional power generated by the afterburner translates directly into increased revenue from electricity sales. Considering the average residential electricity rate in the U.S. as of February 2023, the calculated additional revenue from the afterburner amounted to approximately $25,641.58 per hour.