[Geof3]

That is a significant leak, and as stated above, once the firewall access is removed (very easy overall) I’m thinking it will be pretty obvious. The primary coolant hoses run straight down the center of the car, it is possible a clamp is loose, or you have a small split or something. Usually, if you have a pressure issue, you would be blowing coolant out of the reservoir overflow which should empty on the right side of the car just in front of the rear wheel. Your leak is someplace toward the front of the engine most likely. If it’s anywhere on the front of the block you will notice it right away. If it’s a hose, you might need to put the thing in the air and pull the underside rear panel (easy as well) and look for the “wet spot”. The thermostat hose can be a little bit of a bugger to fully seat and get the clamp on properly. As it was replaced, I would start there...