My setup is hidden and secure under a false floor I built in my hatch.
You can see the tank tucked in the back there on the left side of this pic, and one of the compressors under that board.
Center section is small sealed sub box.. have a crappy grill that i use when hauling stuff to protect the speaker.
Cabin noise isn't bad if you tuck the compressors away like I did. no louder really than a nice exhaust.