Quote Originally Posted by Unregistered View Post
What is this "boost" thing the girls have and how do you upgrade it?
A tank's boost amount increases whenever you 'Upgrade" that tank with copies of itself at the factory. Like feeding a Hetzer to a Hetzer. A five star gains 10% boost from eating a copy of itself while a one-star tank gains a 1% boost. Permanently.

It boosts the EXP gained by the tank from all sources, capped at 30%. You also need a certain boost amount as a pre-requisite requirement to upgrade the tank to elite status.