When Titanium Ribs is installed, most means of receiving brain damage (including stimhack and amped up, excluding brain cage) end up doing 2 brain damage instead of 1: you are prompted to choose the card to discard (because of titanium ribs), and it discards 1 random card as well. You then receive 2 brain damage instead of 1, and your max hand size is reduced by 2 instead of 1.
When Titanium Ribs is installed, most means of receiving brain damage (including stimhack and amped up, excluding brain cage) end up doing 2 brain damage instead of 1: you are prompted to choose the card to discard (because of titanium ribs), and it discards 1 random card as well. You then receive 2 brain damage instead of 1, and your max hand size is reduced by 2 instead of 1.