Thanks guys but i removed the t stat to see if it was it, it was not.

Im really guessing HG. Car is been alot slower lately, and compression test shows like 150 across, 200 wet.

I will just replace head gasket and rings.

 

Your main problem with the temp rising on the highway is due to airflow to the rad. The bumper for the EF is only sufficient for a NA setup. You need to cut out parts arount the intercooler to allow more air to get to the rad and also remove the bumper foam. The disappearing coolant can be one of many things. Some can seep by the rad cap, coolant reservoir or if the rad is a dealer rad, the crimps at the top or bottom. Check all the hose clamps where antifreeze passes. The head gasket would show symtoms under acceleration around town not just on the highway.

I had the same cooling problem on the highway.
https://honda-tech.com/forums/forced-induction-16/speedfactory-c-kit-stock-internal-gsr-2962497/

GL.