800cc injectors?!?!?!?
They will be far to big, 550cc will be more than enough, I guess you must have a shed load of money to go to all that trouble, I would say then the best way to get all the power you want is an engine transplant to a xu10j4rs if you can get one over there, and a supercharger, you can use standard cams and head and use forged low compression pistons, this will give 400 hp,
on the high boost http://www.lynxpowerengineering.co.uk/sc.aspx
also this conversion makes use of the oem magnetti merrelli ecu (for that engine) so it's probebly the most cost effective,
some to think about cause this kind of conversion hasn't been done on a 206 (gti6 supercharged)
what do you plan on doing with brakes and suspension? And the drive train?