Thread:SlyCooperFan1/@comment-25090894-20141103195537/@comment-25370154-20141103201532

If Sly doesn't mind, I'll answer: YES, you can purchase more slots.

Hangar → PS Store → Additional Slots (4 → 8) / (8 → 12) / (12 → 16).

You must purchase the first expansion to be allowed to buy next one.