My only input to this is on my experience with the used '04 FJR I purchased. It had been lowered too far. The guy who I bought it from was extremly short and attempted to make the bike fit him. It was not successful. The bike's ride height had been set so low in the rear that it was actually lower than the front by a large amount. This affected all handling and really messed up the bikes ergo's. After taking it to a local suspension shop, everything was reset to factory spec's and I'm all good.
My point, DON'T lower it too far and I would recommend having a person who deals with spring load, custom springs, etc. do it for you. GP Suspensions in Oregon City, Oregon is THE GREATEST!!!!
Ray