I use the Rockler 4" Dust Right installed on a 20 gallon plastic barrel and my 2HP Harbor Freight dust collector and it works great. I have it piped into the shop using 4" PVC sewer pipe to 6 different locations in my small shop using blast gates to control the flow. I do get a small amount of fine dust in the DC collection bag which could be eliminated using a larger barrel. It accumulates a little more as the barrel fills up with the larger debris.The rockler dustright is 2.5 inch. I bought the Onieda super dust deputy with 30 gal bucket at woodcraft for $215.00. it works great. I have a jet dc1100 and no dust gets into the jet bag. I had a 30 gal trash can seperator before and it worked but dust still got in the jet bag. The Onieda makes 6,5 and 4 inch inlets. Dust collection is about air volume. Don't restrict yourself below 4 star inches.