Just thinking that less delta-p would allow more flow and keep oil from bypass. Plus, those louvers have to create more resistance to "flow" as they change direction of the oil.
"turbulence" in effect. Perhaps I'm wrong... I am thinking less restriction allows for better circulation.
Less delta-p doesn't give more flow unless the oil pump is in relief. If the oil pump isn't in relief, then it's just lower delta-p across the filter, which gives more operating headroom from the filter's bypass valve setting. And oil pumps don't go into relief very often because it takes certain rare operating conditions to make the pump hit pressure relief.
If louvers are formed correctly, there will be more flow area than a typical center tube with holes. Should be slightly less delta-p, but probably only 1 or 2 PSI at most. Center tubes just don't produce much delta-p, unless louvers are mere hairline slits.
If louvers are not formed correctly, they could cause added delta-p across the filter, which would make the filter bypass valve open more often, or in a worse case senario, make the filter bypass run open most of the time.
If louvers were mere slits and very flow restrictive, the filter would act like it was very clogged up, and cause the bypass valve to open. The filter bypass should open before the pump hits pressure relief, but if the right conditions exist it could be possible that both the filter bypass and the pump pressure relief valve could both be operatgive at the same time.