@HeretikJirka wrote:
You got lucky, your PR could have even dropped after installing a material (not just after rebuilding, that is a know issue as well). Look at it this way: during later upgrades, you start with lvl3 car and empty green parts. You need something like 10 upgrades per each part, which means close to 50x6 materials installed (most of the times several of them) and 60 upgrades, totaling 360 actions for something like 200-250 PR raise - which means significant part of them will be without a PR raise.
Your PR NEVER drops when upgrading within the same class. You will never go down a PR when going from a 2 star uncommon to 3 star uncommon. You will never go down in PR when going from a 3 star rare to a 4 star rare.
Installing material and seeing no change, as you move up in the parts class, is more common. But when raising your star level within the same class of part, your PR should always increase, even if just one.