I use the Project Magenta PMDG-737 (no panel) and the B737-700 PMDG CDU type file by Bob Scott. My problem:

During preflight, I see N1 @ 81 on the N1 page.
But on my EICAS the bugs on the N1 gauges moves to 76 only.

For takeoff, when I engage autothrottle and press N1 or TO/GA, N1 moves to 76 only and consequently I need a lot of runway (or even overshoot on shorter runways).

Any ideas?