For 1800 kgs u r obviously talking about the V8 models as the base XT is about 1630 kgs. So to reduce weight i would suggest pull out the V8 and chuck in a turbo barra6 which will save u atleast 100 kgs . Then chuck out the control blade rear and put the rear end of a ute which might help u with another 50-60 kgs. Now put in carbon fibre race seats,bonnet,wheels,rotors,discs,body kit etc. Pull out the rear seat,sound deadening,sound system,air con,spare wheel,airbag and related accessories.
Maintain ur weight at <65 kgs.
Now that will save u atleast 250-300 kgs.
Hope that helps.
Then again i might as well drive around in a gemini (weighs around 1ton) with a fully siiiick turbo and sound system with my seat reclined to a point of no return and my cap backwards.