Haynes didnt do one so you'll have to get a Bently I'm afraid. They are alot more money than the a haynes but get one sent from the American Amazon.com and it'll save you a lot.
The Bentley manual is very expensive (about 80 last time I checked!). I got loads of info from various site like:- VW Vortex Corrado Club USA Edited by: Jon TDI