It will be interesting to see how you get on with this and how much extra distance you get with the batteries. I know the P4 series cannot carry as much weight as the P3 series, but its a payoff as to how much extra energy is needed to fly with the half kilo extra versus the extra power provided by the batteries. Im not sure what the power to weight ratio is for the P4P standard out of the box. Perhaps someone else here will know those figures. I would be trying to source the lowest weight batteries available if I were to do a battery mod to mine, and not necessarily the most powerful in output.Given you have nearly thirty minutes flight time standard, I was wondering why you want the extra flight time, are you going to try and break distance records?