I'm about to build a cabinet to house a router. I plan to use the Kreg fence which I believe has a 4" port but in the cabinet itself, the plans I'm following (From Creston Wood) show a 4" port there as well. I have the ability to do whatever size duct I want and my mains are 6". It would be simple to do a wye to run 6" or 5" to the cabinet and 4" hose to the fence but I'm struggling with what will serve better. The dust collection will come from a 3HP laguna cyclone and the drop will come from above down to the cabinet.

Thoughts?