how do i convert my peugeot 205 gti from 2 wheel drive to 4x4?

Add a tow truck to it.

BUY A LANDROVER!

it will cost more than the car is worth

I don't know how fisible it is, buying a 405 mi16 4x4(very rare) as a donor car and use the necessary parts like rear diff, gearbox and transferbox maybe u can use the 16v cylinder head as well to upgrade the engine.

I agree with Nitro - your best bet is to use donor parts from a 405 4x4 (GLx4 or Mi16x4). You could also use some parts from a Citroën BX 4x4, as that shared a lot of components with the 405.

Take the body off it & weld it onto a RangeRover chassis! But seriously, why would you want to? It'll cost thousands & you'll be ruining a great little hot hatch. Leave it alone!

It will cost you more than the car itself. If I were you I would buy a 4X4 vehicle.

4x4 it? Why? If it has a diesel engine add a turbine and ECU if you so love this car... But turning a normal car to a 4x4 one is very difficult and is rarely worth the price and the amount of work. If I were you, I'd tune up everything else instead... making it look good, sound good.... There are innumerable ways in which your car can reward you...But what you want to do to it is like making a human, who normally walks on two legs, to walk on all four because that way he'll walk faster. You're trying to make a car do things it doesn't want to. Watch out for the retaliation...

You can not convert it without using a full engine, transmission, suspension, and interior conversion. Not cost effective, and you would invalidate any warranty and insurance you may have in place. No 205 is worth spending money on, as they are not worth much now. save your money and buy a scooby do instead