The O&M staff of AES Westover Station wisely took a holistic approach to optimizing combustion within Unit 8's boiler in order to reduce its NOx emissions while maintaining acceptable levels of carbon-in-ash content. The results of major modifications-centered on the addition of a fan-boosted overfire air system-were a 60% reduction in NOx levels, improved unit reliability, and a project payback period measured in months rather than years. As this project proved, the whole is more than the sum of its parts.