I have a problem with high pressure in the cooling system and cant figure out why, I am leaning towards clogged radiator or blown head gasket

 

Thermostat? Your coolant system has to be pressurized to work.

 

I took the thermostat out well not really I modified it

 

Have the coolant tested for hydrocarbons, I forget if a typical coolant tester can indicate if HCs are in the coolant via specific weight.
Look for bubbles in the coolant after the engine has run.
Do a compression test.
Pull the spark plugs, place a white paper towel over the spark plug holes, disable the fuel injectors, crank the engine, note if there is any coolant on the paper towel.