This project investigated the performance of four different brands of commercially available ultrasonic meters installed in an AGA-9 default configuration in two different header designs. The diagnostics from the flow meters were analyzed to determine if they could be used as an indication of bias in the flow measurement. The results from this project were also compared to previous PRCI projects where similar headers were experimentally tested and modeled using CFD. The results of this report are blinded as to meter make/model.