What are the current Stats of Vehicle Armours, weapons and engines and how can I find them? Right now it seems like finding this is only possible in game following them being researched.
Well, when I started playing, I went in single player and wrote down everything. Today, that book is my personal mini wiki
There's a lot of things server can't overwrite without either graphic glitches or clients simply crashing. In short I think the easiest way to say what can be changed is anything that has no visual or numerical component on clients end. Of course there's some a couple of things that can work fine, but it gets complicated.
