Remove boxes.
Don't know if you guys think to keep this item in game or remove, but in my opinion you guys could remove.
Even if it's hard to get one, it will ruin the value of good itens.
Upgrade System
1 - Add a drop rate of upgrade stones, and a even more low chance to drop white stones, from TMQ and UD boss. This way people will play this "dungeons" and farm stones to do upgrade.
2 - Add a money cost for each upgrade try. Not so cheap, and not so expensive. A good value that make people farm money to try upgrade too. This way the server make special the +15 itens, making hard to make, and benefits who hard work to make them.
Well, if this is already ideas from dev team, or other person already make a topic about them, i'm sorry.
I think it's good thinks to make the game more fun and make people play more the game, make things with work and play time, not just lucky and money.