Driven Racing's Block Off plates will stop the annoying and possibly damaging backfires from occurring while allowing you to remove a few pounds in associated valves and hoses from your bike. On late model EFI bikes with 02 sensors, and especially when using Dynojet's Power Commander V with the Autotune feature, the air injection system MUST be blocked as it will introduce additional oxygen into the system which will skew your 02 sensor's values and make it impossible to get a correct tune. Made from 6061 T-6 billet aluminum. The most accurate way to tune your bike on the dyno. A trouble-free way to eliminate unwanted air leaks. Easily remove excess weight from your motorcycle. Comes complete with detailed instructions and an airbox cap. Each piece is inspected and laser-etched with the Driven logo. Made in the U.S.A. Note: NOT legal for street use. For track use only!