yeah it gives you the option of upgrading but you should really check your deck since it doesn't check it for you and sometimes there's just nothing for it to upgrade. (which should really be fixed)
As for chest, if you have a big back, the way it scales is using the "spine bone" so when your back is big your chest will naturally be big. But yeah the proportions defs aren't perfect once you get bigger than 500 Gains.