For those of you that have dry synthetic (washable) air filters, like the Mopar (made by AEM), the AEM spray cleaner is highly recommended. You can buy it on E-Bay for $10. All you do is liberally spray the inside and outside of the filter, wait 10 minutes and flush the filter with water from inside of the cone. Then repeat, once or twice, until the water coming out of the filter is clear. You can then let the filter air dry, or speed up the process with a fan or air compressor.