Thanks for the welcome. Yeah I phoned knights and they said it wasn't possible. The reason I thought it was was I googled 'E46 OBC retrofit' and it gave me a whole list of people who said they had done it. Basically they said as long as my car had the outside temp sensor under the bumper, which it has, and the red/yellow wire for the stork, it was possible with a quick ecu flash from the dealer. Apparantly BMW themselves supply a retrofit kit for about 100 quid and will fit it all in for around 180 quid. I don't give up easily so if I get any luck i'll keep you informed.