Static compression numbers have no bearing on what the head gasket can hold under boost. There is a chart somewhere on the 'net that shows actual cr with different amounts of boost. My 9.5:1 setup at 20psi was actually more like 17:1 cr (maybe it was higher?) with the boost added. That kind of cylinder pressure will find ways out of the combustion chamber that a regular compression test will never find. Usually it will manifest itself by 'pushing' coolant out of the coolant overflow. Yours pushed the coolant into the oil passages, down into the oil pan, and then back through the motor, and that's how it ended up in the catch can. You'll be lucky if you didn't waste any rod or main bearings with that much water in the oil. You MUST change your oil and change out all the coolant before you start the car up again.

Greg

'19 Genesis G70 3.3t AWD
'88 Chrysler Conquest TSI