Thanks Ellis, trying to keep it as neat as possible, hope it will perform well also!

''Edit: could having the option to run it with wheels get it inside 13.6?'' I think we could put it on a diet to get it within the 13.5kg limit, the pneumatic system is heavy, I could do without most of the 1/2'' fittings and downsize, the valve as well, would still work with one half the size (that's weighing 450g alone!)
Wheels instead of tracks can be done as well, and that would loose quite a lot of weight as well considering the track system contains four wheels and two tensioners apart from the track itself.

But for this competition its better to keep to the 17kg limit, still need to add some removable steel armour at some areas, and the flipper arm will not come lightweight! Still not decided how to build the arm, steel or alu tube? Its the part which will receive the largest amount of abuse - so I think it will be steel...

''dont forget that extra 100g very useful '' didn't get it, remind me about that pls