With around seven “Component Slots” each fighter offers Star Wars: Squadrons apparently a lot of room for customization. EA has motives on the official website (via pcgamer.com) explains how these should work in the space shooter.
The usually seven slots (fighters without shield have only six) are divided into three “passive” and four “active” copies that can be equipped with unlockable items. The passive copies include the drive, the hull and shields. A system that is more resistant to blaster fire, for example, becomes more sensitive to missiles to compensate for it; with better mobility, the top speed suffers, etc.
Active systems concern primary weapons, two reserve components and countermeasures. Ion cannons, for example, destroy shields faster than standard laser weapons and can also prepare enemy ships for takeover – but they do less damage to the hull. Furthermore, less damage can be accepted for a higher rate of fire. There is a sensor jammer, a tractor beam, or even an astromech unit that does repairs during combat.