How can you get more horsepower out of your S2000 without turbocharging or supercharging?

To increase horsepower in your Honda S2000 without resorting to turbocharging or supercharging, consider upgrading the intake and exhaust systems for better airflow. Installing a high-performance header and a cat-back exhaust can enhance engine efficiency. Additionally, a standalone engine management system or a quality ECU tune can optimize fuel delivery and ignition timing, resulting in improved performance. Lastly, lightweight performance components and a proper weight reduction can also contribute to better overall power-to-weight ratio.