The reality is, comparing these two propeller sets (the factory Hartzell 4-prop and the MT Whisper Prop 5-prop) is apples to oranges.   Noise (take-off):B1900C:Hartzell 4-blade: 84.0dBMT WP 5-blade: 81.5dB2.5 dB difference1900D:Hartzell 4-blade: 88.0dBMT WP