I did a couple of different fan solutions (6" with 6 to 4 in couplers).
The first one was for a fixed purpose and it is great on air movement and reasonably quiet:
The second one is for when I take it out of my office:
These allow me to have a long run between the GF 
and the fan using a 15 to 25 foot 4 inch duct connected to a 4 to 6 inch adapter and either extend the exhaust to an outside wall or even a carbon filter (to knock down the smell).
Having something that can move greater than 200 cfm helps to overcome the resistance air pressure and keeps the GF under negative internal pressure forcing the smoke and smells out the exhaust.
As an addition noise suppression, the fixed install uses insulated 4 inch duct between the GF and the fan.
or
https://www.homedepot.com/p/Master-Flow-4-in-x-12-ft-Insulated-Flexible-Duct-R6-Silver-Jacket-F6IFD4X144/203420974