Got round to it at last. Waited 'till the first service was out of the way and booked her in. Drove up with the wife on the Sunday (left the kids with Nanny) Stayed at the rather fine Bignell Park Hotel. Good rooms and thoroughly recommended. (details on amd website) Dropped the car in and got a lift to Bicester for a bit of early Christmas shopping in the high street. Had a spot of lunch and a beer in the moons pub then got the return to base phone call. I got home on a quarter of a tank of fuel!!! Sure, it goes better and is much more responsive and the stupid jerky gear change characteristic is all but gone on kickdown, but the main thing for me as a tight b'stard is that it is so much more economical. I've just picked up a 911 (996) so I've asked amd what they can sort out for that as well. I haven't any experience of the other tuners but this option has certainly hit the spot with me.