Blue, when I ran the OEM TStat my temps were cosntantly in the 190ish range. Never past the 0 but they are definitely lower now than what they were. Mind you that was also under a very different driving circumstance - then I was in a big city, deep south so hot as balls always, with very little room to run. Now I'm in a cooler climate and air is usually running through my radiators at 90-110 mph when I am running systems tests
Yesterday I ran twice with the burp valve open and no overflow. Definitely steam coming from the top of the tank though, hard to say exactly from where. Slightly sweet smell in the cabin with the top up (toward end of the drive). Fun note - over 60 mph we can drive in the rain with our tops down! Thanks science!
This morning I ran it with the burp valve closed and again no overflow. Slightly sweet smell coming from top of tank but no steam. Same smell from passenger rear wheel well but no overt fluid loss or steam.
Despite losing what looked like at least a liter of coolant two days ago on my driveway, the coolant reservoir is still completely full.
No funny looking or smelling exhaust under any circumstances since I have put high flow cats on.
I recently drained and flushed the system, and did oil change. No evidence of intermix on either side. With that being said, some years of subaru h-6 (i forget which generation) have head gasket failures and they dont usually see intermixing.
New burp valve is on the way so that will be getting swapped out for good measure. Pressure tester is on its way and I will post results.
Maybe all I have done is overfilled the coolant reservoir (although I'm not sure how I would have been able to physically do that) and the dump tube was just doing its job. If that's the case I will be thankful for the mistake.