Quote Originally Posted by GaGrown
"It's easier to push than it is to pull." Objects that is... Air is just the opposite. The reason your noise was reduced.. Was because your using only half of your intended CFM.. Because your building up static pressure in your can filter.It backs up and turns to negative pressure resulting in cfm loss and compromises the intentended use of the filter. I love ventilation issues as well.:thumbsup:
Okay, so lets give you a task. Fan 750 cfm Vortex. Filter 39" long rated at 950 cfm. For the very reason of not working the fan so hard I went the size up. I want to reduce the noise, I liked it quieter, but don't want to loose cfm...too humid here, got to have extra air flow for the humid environment.

Does it have any help on the outflow by using over sized filter?

How does one reduce noise on the outflow without working the fan more. Can't go under floor boards. Maybe another pre filter same size as can? Will that cut the noise and not over work the fan?