For noise reduction I have been messaging a guy that sells this.

https://www.ebay.com/itm/273926631722?ul_noapp=true

He can redo the design for a m21s/m20 at a cost of 150 EUR and sell it then for 160 EUR. Do you think it would be an option to go this path to make it quieter to run the miner at full speed.  He can put a 6 in exhaust port to flex duct the heat outside.

What do you think?