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Do a search on here for K&N, mac, KKM, they are all companies that make the aftermarket drop in or total open air filters. I have a K&N open air cylindrical filter in mine, I notice a bit of improvement, some don't, some do. But the ones that usually do also have exhaust on their X's. However, it is said to help fuel economy. I would go for it if it is going to be the first mod to your explorer and go from there.