upgrade towing capacity on an 80 series may 95

hi . does anyone know what needs to be done to upgrade my 80 series towing capacity. it is a 05/95 model gxl 1hz. at the moment it is recieving a pacemaker, rebuild, with turbo rods and pistons,switzer turbo, denco cooler, gas,and has well over $17,000 of extra's but it weigh's 3,030 kg's already and the car had 1 person in it and the 110 litre waeco wasn't even in it. neither was any luggage. i can up grade it's vehicle capacity to 3,350 kg's but i loose on it's towing capacity.it is rated at 2,500 kg's. so i need to upgrade it's towing capacity to 3,500 kg's as iam looking at towing an offroad kedron which weigh's, in total, 2,800 kg's. any comment's or other would be very appreciated. thanks. buddha.