I have read the trick of filling plastic tanks with hot water and then attaching a bicycle pump to expand them - per the video below demonstrating the process on a DRZ. But not to a Gili tank.
http://www.youtube.com/watch?v=8h7BOGlNO8E
The offsetting argument is that by "expanding" the tank, you are effectively making the plastic thinner in some areas and potentially decreasing the robustness of the tank. I can see the merit in this logic and thankfully, for me, I don't need more than a 500k range. At least at the moment
