The aftermarket one I purchased also didn't fit very well.
The OEM size for the pacifica (using my own ruler) is 8.25" x 9.8" x 0.8". The aftermarket filter I received from Wilson Automotive Warehouse on Amazon is 7.8" x 9" x 1.2" (see photos).
The pacifica internal air filter port has specific guides for the OEM filter (see photos). However, since the aftermarket is not as wide, it avoids those guides, so it still technically fits. However, I can see where air will now slip past the filter because it doesn't cover the entire area between the blower and intake. So my non-scientific estimate is that 8-12% of the blower air will not pass through the filter, whereas the OEM probably doesn't miss much.
Pros: It's much cheaper to buy this filter than OEM. Also, because it's thicker than OEM, it would presumably be able to filter for longer, because the filter media has more total surface area. The filter material itself seems sufficient quality as well.
So the question becomes, is it really worth spending $15-30 bucks MORE on a filter that fits perfectly? I'm not so sure, especially because this is for a vehicle that constantly cycles non filtered air through doors, windows, and ambient dust. Further, I don't believe the carbon "dusting" in the OEM is enough to make much difference.
My only concern after resolving the cost vs fit question is that any larger particles that slip past the filter could get into the blower assembly, etc. Given the size and quantity of tree junk that came out of the OEM filter when I replaced it, this seems possible, though unlikely to cause issue. Though, over years of time, the blower assembly could start accumulating dust, which might contribute to premature failure.
Side note: You can get an OEM filter for $22.34 shipped right now (Ebay item #192131842882).
Last edited by dotbot; 10-11-2017 at 05:36 PM.