I have two hours on my 3100ZP and consumed 2.5 gallons per hour. I'm glad to hear your efficiency has improved. I'm hoping to get to 1.6 GPH.
Have you noticed any increase in HP as the motor has broken in?
I removed the small metal baffle under the deck by the discharge chute and noticed less bogging of the engine in thick bahia. I'm going to remove the stripe kit next as it does no good that I can see. I'm happy with the machine so far.