The way I understand the learning/settling in issue within the ECU is that it has a certain amount of built in automatic adjustment, so when a base map or remap is installed the ECU can adjust certain parameters ignition timing,fuelling, boost settings slightly to get the best results for the engine in question, this isn't a new thing the mk4 Golf and older VAG cars did it as well.
When intially mapped my car did low 290's and 2 weeks later it did 298, but this could also be down to a few more miles on the car.
Hurdy, did you manage to get a figure before the carbonio, as this is the only difference between our cars it does make me think.