warranty

Does changing the exhaust and remapping void the warranty? How much can you do to the bike without voiding the warranty?

I recently purchased a new FZ6R with the usual 1-year warranty. The dealership offered me an extended 4-year warranty (5 years total) for $690. I asked if I could pick it up later during the first year. The answer was "yes, but it might cost $750-790." So, I have a few questions... Please...