I run my BakPak with a MJ900 and the venturi kit. Pulls at least twice as much as the Rio 800 did when it worked at all. It takes a little adjustment to get it just right and you have to keep the tube leading into the collection cup pretty clean, but I'm very happy with it. Haven't done the airline mod yet. Mine is actually a BakPak I that I bought used fairly reasonable, so I didn't mind spending a little to upgrade it.
Here is another link I had for a while with some more info and the airstone mod also:
CPR BakPak tuning