Pete makes good points, and in short, what you have is pretty much it. Bars, factory set. No consumer calibration.
However....there is no substitute for an accurate in-deck mechanical fuel gauge. Twist the pie plate and take a look. When ran twin Yamahas....always put faith first in the mechanical tank gauge versus the electronic gauge.
All boats should run a mechanical fuel gauge....and a real compass. Forget the smart this and that.....when you're in the fog....and your smart phone dies....and the batts die....old school will get you home.
