Quieting a Generator

• Road legal limit is 74dB.
• Duromaxx 10kW is already 72dB and going down to 45 db at idle. [1]
• Just deflector - https://www.youtube.com/watch?v=5zwc5mdEbDI . Sound does not come only out of the muffler.
• Baffle box - https://www.youtube.com/watch?v=DH4L1rTral4
• GoBoard tile board - https://www.jm.com/en/home-insulation/tile-backer-board/goboard/
• 85 to 75 db - [2]