This quarterly report documents work performed in Phase I of the project entitled: ''Technologies to Enhance Operation of the Existing Natural Gas Compression Infrastructure''. The project objective is to develop and substantiate methods for operating integral engine/compressors in gas pipeline service, which reduce fuel consumption, increase capacity, and enhance mechanical integrity. The report documents the second series of tests performed on a turbocharged HBA-6T engine/compressor. It also presents baseline testing for air balance investigations and initial simulation modeling of the air manifold for a Cooper GMVH6.