Plug nozzles with two types of 40-spoke noise suppressor were tested at free-stream Mach numbers from 0 to 0.45 and over a range of nozzle pressure ratios from 1.5 to 4.0. In addition, an unsuppressed plug nozzle and a Supersonic Tunnel Association nozzle were also tested to provide baseline levels of thrust performance. The unsuppressed plug nozzle had an efficiency of 98 percent at an assumed takeoff pressure ratio of 3.0 and at Mach 0.36. At the same condition the suppressor nozzles had efficiencies of approximately 83.5 percent.