I don't know anything about WIX filters and have never seen one, but keep in mind DC changed from "paper" filters to "fleece" filters awhile back. The WIX filter is "paper" NOT "fleece". The pic and the filter information below were taken from their website:

http://www.wixfilters.com/filterlook...&TempYear=2004

Me, I'd stick with the recommended "fleece" filter. I have seen the FRAM, STP and Mobil 1 aftermarket filters... they are paper and of poor quality. They are no where near the quality of either the old DC paper filter or the new DC fleece filter.



Edit: I just checked with a few retailers in my area. The WIX filters for the Crossfire/SLK320 sell for $21.00 - $22.00 plus tax. My DC dealer sells the "fleece" filter for $19.50 plus tax. So... no $$$ savings on the WIX filter and I would guess they are of lessor quality as the OEM filter.