Maserati have a learning system built in to the ECU, which adapts eventually to the driving style of it's regular driver, it will need a few journeys to get to your peak performance.
I hope this helps..??
To be fair, you're not comparing like with like there Mike. The Trofeo runs much stiffer suspension and ARB, so the tyres need to perform a very different task.
The Trofeo cars also ran lower profile rubber 245/35/18 fronts and 295/30/18 rears
The Trofeo cars run the same profile as the GS albeit on different tyre sizes..!!
TrM5, an easy way to tell what is on the back and if the valves are working, is drive it in normal at around 3K rpm then hit the sport button, you should hear a different noise..?? The valves could be stuck, or the electrics are not triggering them..!!