Hi Lizard,
I'm not technical so I'll let the guru's give specific advice in due course. However, I would add a cautionary note.
The Auto Aeros' were limited to 200BHP as opposed to the Manuals 225BHP as the gearbox wasn't as strong. I'm sure the gurus will be around pretty soon to slap me down if I'm scaremongering but I recommend that you have a good hard think before you start adding any serious power upgrades.