Super-easy install and adds about 1 HP to all 2004-2007 YFZs. The stock ignition system on the YFZ has a flaw and the Sparks Throttle Position Sensor Bypass Plug will eliminate that problem. Off idle up through mid throttle, the CDI transitions between maps based on information from the TPS. For some reason the bike doesn’t accelerate as smooth and hesitates as well as idles rough. The Sparks TPS plug solves all of these problems. Simple to install with no downsides. A MUST for all YFZ owners.