I just got done connecting my modem directly to the green UPC cable. My power values have indeed improved. They're now approximately +2dBmv higher across all 4 channels.
Power Level Signal to Noise Ratio
Channel 1: 0.7 dBmv 39.7 dBmv
Channel 2: 0.5 dBmv 39.9 dBmv
Channel 3: -0.3 dBmv 39.4 dBmv
Channel 4: -0.7 dBmv 39.3 dBmv
Channel 5: 0.0 dBmv 0.0 dBmv
Channel 6: 0.0 dBmv 0.0 dBmv
Channel 7: 0.0 dBmv 0.0 dBmv
Channel 8: 0.0 dBmv 0.0 dBmv
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Upstream Channels:
Power Level
Channel 1: 46.0 dBmv
Channel 2: 0.0 dBmv
Channel 3: 0.0 dBmv
Channel 4: 0.0 dBmv
Total net gain: +extra hole in my wall, speed difference 0