I've got a compression tester, but nothing else available to try a leak-down test. I'm not quite sure I can get my tester down into the spark plug well.

I keep looking for oil in the coolant and coolant in the oil. I see none. I don't know how I could be burning that much coolant w/o seeing some white smoke. This is crazy.

The coolant loss is getting extreme. I topped off the reservoir this AM w/ 1/3 gallon. It nearly overheated when I was arriving at work (~5 miles). Poured another 1/3 gallon, and got within a few block of home when the coolant began to boil out. Parking, I was greeted with the view of the coolant boiling out.

After cooling and relieving the pressure, I added another 1/2 gallon). This is just clean distilled water, BTW.

I'll pull the plugs and check them for clean - that may be the only way I can tell what's happening w/o some more sophisticated equipment.

Is there any way the turbo could be the source of the loss?
Is there any way a bad thermostat could be contributing?
Is there any way I can keep the system from fully pressurizing?

I really need the car for a few more days. Head Gasket kit and a cam locking tool is on the way.