The existing systems works fine with the present items. I'm questioning whether it will work with more advanced items, though. Take HPA or APA MKII for examples, it would seems strange if the same NPC teacher who teaches you beginner level armor was to also teach you those advanced techniques for armor that you don't even have yet. It would work only if you can add a certain 'check' before they appear in the crafting categories, like maybe a level check or if certain locations are discovered like for example they appear only when PC enters Military Base/Navarro. About the Fuel ammo, here's an idea. It is possible to just delete them as items from the game and then re-create 2 identical items in their place like the new Bozar ammo for example?