Small bug but when you hit the max upgrades on crit it still displays the exclamation mark for it when you hit the point where you could buy the next level
My current build: http://i.gyazo.com/8bef8002411f85adcec3c5febb50c019.png
Remove a heat vent to let the heat build to near critical and then replace it. Do not use any heat exchangers
Do you buy new hero?