I'm not sure cutting open a filter really tells anyone a lot as far as what the filter can or cannot do. The only real data that I've been able to come up with on filters thus far is how they hold up to certain flow rates and pressures. The Fram-branded and Fram-produced filters seem prone to collapsing when used in high flow, high pressure applications.

I'd like to know what the micron rating is on Fram's filter material versus Mann's, its tensile strength, bursting pressure, etc. Those things are a little tough to gauge by simply cutting the filter open.