Mike Borgelt wrote:

When you do the performance calculation correctly you are in for a
surprise.

Jet engines have more power available the faster you go.

The downside of this is if the specs are for thrust in Newtons
available at a certain airspeed (not 0). At 0 airspeed, it
may be that the AMT-400 puts out significantly less power.
This would extend the takeoff roll some, and decrease efficiency
at any airspeed lower than "spec."

Or maybe the spec is for thrust on a test stand, who knows?