Don't forget the infamous "ByPass Pipe" and "Y Pipe" culprits. Also check the Degass Bottle Cap for a cracked seal that could be letting coolant steam out of the system. And also the heater lines going to the rear A/C unit thru the undercarriage
I would run the engine at normal temp for like 20 mins or so, place a clean cardboard under to cover the whole engine bay area (including the firewall) and try to smell for coolant, If you can smell it the leak is big enough to cause big trouble and also checking the cardboard underneath for new coolant drippings which may need to be left overnight to catch!