This is an excerpt from a dust collector review that is no longer available on the Porter Cable website.
Good stuff.
Running those large roundover bits in my table is a little on the exciting side, but I've done it.
Here is an option that can be purchased at common retailers in the ductwork section. Airflow increased by 10% when I added an un-modified 5" to 6" reducer fitting to the end of a 5" duct recently. You could cut along the orange line and this would likely increase airflow further. Measurements were made with a pitot tube and digital meter. I will post details in a separate thread very soon. Cheap and readily available, many sizes available, what's not to like?
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