I'm looking for guidance on how to update the instrument cluster in my 2007 Ford Focus. Basically, I'm looking to replace my present cluster with one that has the tachometer. Removing and replacing the cluster looks simple enough, my questions are... What about the electronics? How do I update the mileage in the replacement cluster to match my original? I want everything to be legal and I'm also not sure about what parts of the car 'talk' to each other electronically. Any advice is appreciated. Thanks.