As you are aware, custom ship has become a powerful tool to destroy others' fleet. And we will have to nerf it again since maintenance/upkeep cost is not enough.
I will start with good news first. You will be able to equip more than one module of the same class if your ship hull supports it. That means you will be able to have more than one weapon equipped or reactor or shield.
Plus some energy issues will be solved due to value change from fluid (energy may change due to reactor) to static (energy fixed value).
To end with good news, a new module class will be added, CPU.
Of course, with such big improvement, nerfs must be applied, and we will start from Weapons. Their power will be reduced by four times and their rapidfire reduced to one. Since you can equip multiple modules now, there is no point to have insane rapidfire values against common ships, making a powerless player even more powerless.
Other thing is, all default ships will have rapidfire agaist Mothership depending of which modules it has equipped. That should balance the things against those who are impotent on finding modules and/or those who focuses only in mothership (when the game has other ships to be used).
For this multi-module support, players must expect with Reactor nerf and increased rarity on expeditions. Their power may be lowered by 2-3x.
PS. Players will be able to equip only one non-repeated event module (e.g., players can not equip 2 Stellar Cores for insane amount of energy)
This update will be on effect soon together with other changes and new events.