I use a 1.75 hp powermatic motor and fan, into a Onieda super dust deputy with a 5" inlet and 5" tubing all over my 3 car garage shop. It all works well. Have a large .5 micron Wynn cartridge filter on top. Added a magnahelic guage with tubing sealed into top of cartridge filter to tell me when back pressure was building in filter. Usually only have to clean filter cartridge once every 2-3 years. Most of tubing is hvac big box stuff but for long ceiling runs I used nice smooth 5' thin wall pvc. Not easy to find but I live in an agricultural area and its avail. I've also tried to open up most machines from 4 to 5" for good dust collection at source. Randy
Randy Cox
Lt Colonel, USAF (ret.)