[KingLT1]

The only way you lose mileage by turning off AFM is if you routinely drive on a flat road where the engine stays in V4 mode and it's about 1mpg tops. Turning AFM off is one of the best things you can do for the A8. And no you do not need to delete the AFM lifters and all that. The M6 LT1 is the exact same engine with the same AFM hardware in the engine... AFM is simply not activated in tune nor does it have the AFM valves in the exhaust.