I'm planning an addition to my shop and will be redoing my dust collection system. I would like to run ductwork under the new concrete floor to go from my Oneida dust collector to the area where my table saw and jointer will be located in the center of the shop. Both of these tools have 4" ports) Question # 1: Is this a good idea? 2) Although my ductwork is metal, would a 6" pvc pipe be better to use underground? What type of connectors would I need to go from the 6" pvc to the metal ductwork above ground? (the oneida outlet is 7" and I do have a metal reducers) Thanks for any suggestions you may have.