Three years ago, an article in POWER described how Cheng Power Systems, by modifying the combustors of several popular gas turbines, had used steam injection to lower the units' NOx output to about 5 ppm-but some models had substantial CO levels without combustor modifications. Since then, the company has developed new combustor nozzles that recently proved capable of limiting a turbine's emissions of both NOx and CO levels to even lower single-digit levels. Field test results for a naphtha-burning LM2500 are presented.