FYI the 4'' 175cfm oracle fan is LOUD! they are advertised as 'extremely quiet' on the website i purchased them at. Maybe the motor is quiet, but the air rushing out sounds like a hair dryer. I hope my DIY muffler and carbon filter help.

I don't want to be like my friends grow and her little sister asked "why does it sound like you have a vacuum cleaner in your closet?"