Okay, here is what I have so far.

I posted a picture of the two filters side by side

http://www.greenhybrid.com/share/image765.html
The OEM filter is on the left. As you can see, the Purolator filter has a different end cap as was mentioned by Steve I think. It doesn't LOOK like a big deal at first but I measured it and it looks like this:

OEM: 2.75" overall height, 2.6" element exposure, 20.4 sq. in surface area
PL: 2.75" height, 2.2" element exposure, 17.3 sq. in. surface area

The surface area is just the area of the exposed element as if it were a flat surface, not the actual area of the paper.

The other thing I noticed is that the OE filter has 65 pleats where the PL has only 62. This leads me to believe that the OE filter has more surface area of the actual filter paper. The pleats on the PL appear to be thicker and heavier than the OE filter.

The felt rings on the PL are a tad thicker but are also softer. The OE filter is made in the UK while the PL is made in Thailand.

The PL filter weighs about 16% more than the OE filter. I am guessing it is due to the additional plastic in the cap.

This was all I could think of doing for non-destructive tests. I may still do some more tests (for flow rates and actual areas of the paper, etc) but too tired tonight. Gotta go put the kid to bed soon anyway.

I am now up in the air as to whether I will use the PL filter in the FEH.

Any thoughts?