I also use the WIX 7712 or NAPA 57712. They both fit and function. Further investigation leads to 2 things about the OEM filter. First is the bypass of 23 PSI and second is the flow at 12 GPM. Our oil pump is a high flow, high pressure type and so far the OEM is the only one that meets both requirements and fits the small space on an XT. The WIX filters flow at about 9 GPM. My research has been on Bob is the oil guy, Forester.org (here), NASIOC and manufactures web sites. Once my stash of 7712's are gone am going to go with OEM on both my XT the 2001 NA "S". Another interesting filter is from Denso # 150-1011 for the turbo engines and 150-1006 for NA, non turbo. I have no idea why Denso offers 2 filters but I would bet the 150-1011 is smaller than the NA one. FRAM also makes a subie specific filter number PH9715, maybe it's an OEM in a different color can? I have never found one to look at.
How important flow and bypass are is not really not know since both type engines have run many 1000's of miles without issue using many kinds of oil filters regardless of brand the most important thing is to change the oil. That being said I want to help my turbo all I can so its OEM for flow and pressure, no others seem to do the job better.
