Does anyone believe this? I've completed 12 missions, and the mission number 13 started. It gave me the message that I've completed vigilante missions and that my armor will increase. However, my armor progress bar didn't get wide, it stayed the same size it was before. I had very little health so I had to stop vigilante mission number 13 and go home and save my status, because I barely survived and had soo mutch trouble completing those 12 levels...
I got up to about level 30 roughly using the tank. I had no armour to start with (I had already done the basic 12 missions and gotten the 150% armour, this was another attempt) and after getting so many missions completed I did not get any armour (my tank overturned and stopped further missions). I think therefore that level 12 is the maximum for getting anything. When I got to this high level I was getting about 40 seconds per mission and I could not keep up with the time limit.
I will temp edit it out until its proven true...