Hey NB217, I pull the air out rather than push it out of the GL60. I have the Active Air 4" 165 cfm /w speed controller at 1/2 speed, the smallest Phresh filter 4x8 (rated at 150 cfm), and Phresh silencer on a shelf just above the GL60. I placed a foam sleeping bag pad over the fan and silencer for additional sound dampening, but left the filter free to breath (see pics 4 & 8.) For lights 250w MH/HPS in a 17" cool tube which fits well in the GL60. I placed the ventilation system outside and just above the tent to maximize grow space. It was also easier and I love simplicity.
Also put a webcam attached to a old laptop in there so I can monitor the temps via remote desktop connection.