Hmm. There is a scenario which seems to fit both Frontier's wording and the larger capacity being claimed by some:
1. The Panther has two size 7 and two size 8 slots. Of these, one size 7 and one size 8 are restricted to cargo racks or fuel tanks only (so you can't have both a size 8 shield and a size 8 fuelscoop, for instance).
2. There is a new module, the Optimised Cargo Rack, available in two sizes (7 and 8), offering 50% more capacity, that can only be fitted to the Panther.
3. These will fit any size 7 or 8 slots on the Panther, not just the restricted ones.
Analogy: Saud Kruger ships and Luxury passenger cabins. These can only be fitted to SK ships, but even when these had restricted slots, we could still fit Luxury cabins in unrestricted slots too.
If true, that would add 192t to previous calculations.