The Wix XP flows longer before it clogs up than their other offerings, flow isn't the issue I don't believe. Flow is pretty constant. Personally, my opinion is a name brand or OE cellulose synthetic blend filter is the best. I believe the cellulose scrubs oil finer during longer use, and also takes out a little water. So my choice would be the Wix standard or Napa Gold. They haven't shown problems I am aware of. Too much is put on the rapid efficiency test, proven by the fact a Toyota copy filter beat the Fram Ultra in particle removal at the end of an oil change interval in a believable, documented, test run.