Originally Posted by
Less Hair
It has a modified high lift system, different flap positions and different FBW software that could result in improved take off performance.
The main factor here is likely to be the changed wing flap settings. My guess is the t/o perf isn't going to be that much better, but apparently takeoff flaps now depend on the FMS and will vary per takeoff, so clearly they're trying quite hard to improve performance, likely because that's the main thing that you lose from the 757 if you're switching away from it.