I first purchased a "cheaper" set of air filters off the internet. When installed on my bike I had nothing but problems. After trying several things to fix the issue, I found out that the design of the air filter was limiting air flow and partially covering the air/ fuel mixture screw. I spoke with a represtative at Dennis Kirk and he pointed out that K & N is a leader in the industry in performance and design. They do the proper testing to insure you get the best possible product. The represenative easily talked me into going with a proven product from a company that stands behind their products. I experienced what happens when you buy a "cheaper" version from a company that does no testing. Hats off to Dennis Kirk and their staff for the vast product knowledge and their ability to explain why you are best to purchase a quality product! My biek is running great with the new K & N Air Filters. Thanks again Dennis Kirk!!!!