Okay, so I have G75 that has descent compression when it sits overnight, but after it runs, even if it runs for 5 seconds, the compression is nearly non-existant. I've already replaced the ring, and that helped a bit, but still cannot start it by hand, and still the hot/warm compression is terrible.

Fuel is 10% omega
Head is shimmed an extra .008" higher than stock
Prop is mas 13-6
flying RPM is normally 10600.

Any suggestions about what to check would be appreciated.