How do I upgrade my booster storage?
Solution 1:
It looks like one way to increase this by 10(!) is to acquire the Bassani Butchers deed in Mor Ardain. You can get this at development level 1.
You can increase it by an additionall 10 by getting the Hanoon Deeds (Hanoon Fishmongers, Mor Ardain, not sure on dev level).