The spin on filter adapter thread in the Series section reminded me that I never posted this here.

I came across this some time back:
http://www.bullittarchive.com/5000/5...arison_Kit.pdf
Note where the by-pass valve is located in the expensive Mobil1 and K&N filters.
I've always trusted the Wix quality. Looks like the trust is warranted.

I also use Baldwin B2's and was thinking about cutting one open to check, but this video shows their bypass valve is also well placed.
Just jump to 7:00 so you don't sit through him confessing to making meth or something (and cussing the two cheap filters).