having owned 2 twinturbo XR4x4s and a 24v car i'd reccomend only doing this conversion if you can find a complete kit cheap. like 500quid cheap

if you have any bits missing youre gonna have to spend qutie a bit of cash getting stuff made up

do consider a 24v conversion. these are not as quick, but theyre 90% as good and piss easy to do and also very cheap.