Contrary to what you may have heard or read, in the USA, a K&N Filtercharger will not void your vehicle warranty. The Magnuson-Moss Warranty Act, passed in 1975, prohibits a manufacturer from conditioning its warranty of a consumer product upon the consumer using any article or service (other than one provided without charge under the warranty) which is identified by brand, trade or corporate name, unless expressly authorized by the Federal Trade Commission. If the manufacturer does not provide air filters free of charge, they cannot void the vehicle's warranty simply because you have installed an aftermarket air filter.
Letter from K&N Regarding Vehicle Warranty and K&N Replacement Filters[/b]