The new Railjack system in Warframe is a pretty great change. Digital Extremes has added a bunch of refined versions of the features that already were in the game, and that makes the gameplay much more enjoyable. The mod system has now been shifted around a fair bit. This is described by DE as Railjack 3.0, adding a new and more comprehensible dimension to the space ninja game. That Railjack 3.0 upgrade has replaced Avionics with a more recognizable mod system. Now, the Railjack works much more like the weapons and gear you’re used to.
There are three types of Railjack mods now:
Instead of having to handle all of the different types of Avionics, you just put the right kind of mod into the right slot. To place mods, open the Plexus within the Dock and you can scroll between each option. You can also access these systems via the Orbiter, or the Dry Dock in any Relay.
Mods can be earned from enemy drops in Railjack missions, so get out there and start farming. But if you want to get more powerful, you need to upgrade them first.
Capacity and upgrades for the new Railjack mods works just like the other mods in the game. When you want to increase the power of a mod, you need to expend Endo to get a mod to a new tier. Each new tier of a mod will take up more power capacity. And the Railjack has a maximum amount of capacity that you can make use of.