I currently have the stock Air Assist for my TS2-20W and have upgraded to ACO-328.
However, although it’s more than double the air volume, it’s lower pressure.
It also used 9mm ID hose, which while can be fixed by using a bigger hose, the L shaped connection on the laser head and the nozzle it connects to is made for the smaller stock air assist. This restricts air flow a lot. Worse still is internally the L connector is only about 1mm ID internally. This compounds the problems with the ACO-328 being low pressure/high volume.
“Just buy a compressor” is not the answer I’m looking for.
How can I adapt the head/nozzle to directly take the 9mm ID hose?
Maybe you can get a new air regulator. Search for a bigger OD.
That’s not an upgrade, but a downgrade. The ACO pumps are aquarium pumps. Those are not meant to be used as air assist pumps (though very popular because they are cheap). Those pumps have no pressure, as you noticed. And they are not built to provide constant pressure. So it’s a bad choice, even if you would rather not hear “buy another one”. The ACOs are NOT made for lasering.
Anyhow, I think the easiest way would be to use a 3D printer to create an adaptor.