I have not managed to do that as yet however with 500 cfm it will clean the house of everything very quickly. The rest of the setup produces a lot of smoke and the “Blue whale” (it is a giant blue filter feeder) gobbles it up pretty good though a fair amount is also escorted outside,
However I started to make a reducer and included a free pattern here.
You will find that a small folgers coffee “can” is just the right size to fit a 4" hose so i am trying to fix the sides with Celastic ( the link for it is at the end of that thread) though fiberglass might have been a better choice had I not already had the Celastic.