Started replaying the Homeworld 2 campaign, with my overpowered Mothership in hand.
You replaced the Mothership point defense guns with Dreadnought cannons, didn't you.
Nope. Increased their range from 2500 to 4500, increased rate of fire, but decreased accuracy and damage to compensate. Now it looks like a real point defense(read: bullet spamming) weapon.
I also added 4 Ion cannons and torpedo launchers, although it looks like the torpedos don't really work ... Oh well.
Oh yes. Gave my interceptors the ability to fire missiles, and strapped a rear-facing point defense weapon to bombers, a pair to resource collectors, and 4 to mobile refineries.