In 2007, the Progress D-27 was successfully modified to meet the United States Federal Aviation Administration (FAA) Stage 4 regulations, which correspond to International Civil Aviation Organization (ICAO) Chapter 4 standards.[67] A 2012 trade study projected that propfan noise would be 10–13 decibels quieter than allowed by Stage 4 regulations.[68] Stage 5 noise limits reduce the limits by only seven effective perceived noise decibels (EPNdB),[69] within the propfan noise envelope. The study also projected that open rotors would be nine percent more fuel-efficient but remain 10–12 decibels louder than turbofans.[68] Snecma claimed that its propfan engines would have about the same noise levels as its CFM LEAP turbofan engine.[70]