How is the new G56 ECU R1NGA? I notice you have it now according to the car register details. I assume it isn't locked and you can alter the settings? If that is the case you could alter the Wheel Speed Gear Factor numbers for the speedometer to correct the 8% over read, that Morgan seem to be unable to do. There is a procedure in the S&S manual. A small but annoying item I know and it will also knock 8% off your recorded mileage, legally.