Thanks for your answers.
But I'm still struggling to understand the Lightweighted Armor mod from engineers.
The mod reduces the Hull Boost - and I'm struggling to understand what effect this has (beside a reduction in the Armor value) on the agility of the ship.
The Heavy Duty Armor mod increased the Hull Boost and the resistances.
The Heavy Duty Armor mod looks like a mod without any drawbacks, while the Lightweighted Armor Mode has the "drawback" of a reduced Hull Boost.
Since the reduced fuel consumption of a FSD gets displayed as a "red" change (I guess red indicates bad) while it is a very positive effect, I'm now wondering if the "red" reduction of Hull Boost actually increases the agility of a ship as a positive effect.
(And the description of the mod is wrong as it says that it reduces the mass of the ship, but it doesn't).