Well, after loosing maybe 4-6kg off the exhaust (Make sure you ditch the heavy CAT), the next heaviest part that can easily be changed is the wheels….. £1000-£1500 should loose another few kg.
MTs don't have much bodywork, and I doubt you can get carbon replacemnets anyway, but you could maybe trim another couple of kg by ditching unnecessary stuff like indicators and mirrors, changing the bars for Renthals, putting on smaller headlights, trimming the tail unit, fitting a smaller numberplate
I'd say you could ditch 10-15kg, but that it's going to cost £2500-£3000 to do it.
Which begs the question – "Why not just spend the extra on a different bike?"
e.g. Monster 1100? That won't be much heavier than my 696. And that felt lighter than some push bikes I've ridden! 🙂