For a ship that has a mass of 10.000, it moves way to fast even without aux thrusters, i would cut its maneuverability by half and give it 1/3 of its acceleration.
Compared with my Vatican Mk.III, which is just about the same size. from top speed to mass and an image so you can see size difference.
Vatican Mk.III 10,2.5,2.5,2,0.50,4500
Faithoper 20,10,7,5,3,10000
It's not overpowered by any means, i can easily kill it. but it runs circles around other capital ships and that feels a little odd.
Oh and the assault variant has an empty small slot by the engines, intended to have a railgun there.