Engine stacking is the biggest advantage a player can get over the AI (even if you improve the default blueprints, player can always out do AI). In my games I remove all but one engine and make it One Per Ship, then each engine Tech grants additional movement bonus, couple that with a Engine Augment component it sticks the AI on an even footing vs the player, movement wise. (give or take 4-8 move depending on Traits and Tech tree). Its nioce to see AI with 30+ Moves tbh.
All ships have a Base of 1 Movement.
Engine Core grants 3 Movement (1 per ship)
Engine Techs grant +2 Movement per Class Tech.
Engine Nacelle's grant +10% Movement (Stackable, 14 Mass + 5% Scaling)
There are 5 upgrades available which brings Movement upto 14 base. Plus any Nacelle's you stack, Traits and Techs.
Thrusters add +2% Movement.
Thats the System.