Hello, I have a bathroom that needs roughly 65cfm of ventilation. Because of the attic configuration and trying to make future service easier, I would like to install an inline fan farther away. So it's going to go from two 4" duct ceiling grilles, short flex duct to a wye, 27" flex duct, inline fan, short flex duct, to finally a roof cap. With that configuration, what size ducts do I need and the fan cfm? Off the cuff, I'm thinking 4" ducts from the grilles to 4x4x6 wye to 6">4" reducer to 4" 135cfm fan? Am I even close? Thank you in advance for reading!