I filtered three batches on Friday using the 158116 housing and a P5 filter. This time, I was able to get the hoses all the way onto the barbs and I had almost no air at all. Unfortunately, the fit was so tight that I broke one of the barbs trying to get the hose off.
Off to Home Depot to see if they have a worthy replacement. But the moral of the story here is make sure your hoses are all the way on those barbs. That made the difference for me.
I purchased a 158326 housing from Filtersfast and will do some side by side tests soon. I'll post up when complete.