Upgrades are necessary. sk8 found this out on his second 100% Good Karma run. The in-game counter (visible on the save screen) doesn't reach 100% unless you have all the upgrades for your Karma.
There's no IGT for this game. You could manually remove loads I guess, but nobody's interested in doing that. They shouldn't vary much across PS4's anyway.
so i watched sk8's ending where he said you need the upgrades. you don't. when he saves his game at 8:31:14 on the video, he has no recent save data. and when he opens up the load files to check at 8:31:25, he has the 100% save file before getting the upgrades. the other two files are auto saves that were created before he did the final graffiti art.
so no you do not need all the upgrades.
Hmm, well I'll admit I didn't look that closely. But I did remember him saying he needed them.
