Someone is selling the K&N style air filters on ebay. About $69.00? Go to ebay motors, click on motor cycles, put in xciting 500 and search in parts and accessories catagory. Seems like a lot of $, but stock paper is not cheap either. This filter will last forever (just clean and re-oil it once a year at most), and it filters better. No jetting required unless you have a carbed model with diff exhaust? And maybe not then if exhaust is not to (wide open).