I would figure that since it is twice the size as a .46, it would use close to twice the fuel. I have both an OS .91FX and a Magnum .91XLS and, as I recall, I have either 14 or 16 ounce tanks in the planes. I am using Ultra Thrust tuned mufflers on both.

.91 4-strokes are more economical, but 2-strokes go through a lot.