So I was watching a really good youtuber z28 online in one of his videos in Japan and he points out that his Citreon wasn't as powerful because the engine wasn't upgraded with mileage points yet. He said he noticed that even though BOP is supposed to remove the upgrades cars still felt faster after the upgrade. I never bothered to upgrade because I only play in sport mode. Is this true? Has anyone else noticed cars performing better in BOP races after upgrading the engine?