Hey thanks for the replies guys.
I think that adding extra weight into the compartment would be ok to see how it flies, i'll try that one thanks RC Sumo.
I realise how big a difference that sort of extra weight would make, and that is why i thought i would ask before spending money on battery packs, these forums are full of stuff for n00bs like me, maybe too much sometimes, lol, but i'm slowly finding out the things i need.
Now if only i could find the bottle to go fly/crash this thing and see what it is really like