My water line from thermostat housing to water pump is blowing off above 3500 RPM. The engine is running cool. Do I have a head gasket issue or thermostat housing obstruction to bypass circuit? Also, can I remove the thermostat without removing anything else?

Took out a restricter and replaced thermostat (160). Now the only issue is that the engine never exceeds 140 (as measured on a bypass line). Should I try to resolve this?

same thing happened to me in june. toasted my engine. have you found anything out on why?

You can remove the T stat, just be careful not to break the white plastic retainer.

Just remember, EFI engines like heat. If it is in tact an EFI, you will soot the transom, get terrible fuel economy, and most likely wash the oil off the cylinder walls.