Air release from compressor safety valve.

Something is causing too high head pressure. Put another gauge downstream until you find the pressure drop. At drier? At outlet of drier? Don’t rule out new part cuz they are new. Or it’s inside a fitting or part you haven’t changed yet?

 

While not all compressors and charging systems are
equipped with a discharge line safety valve this component
is recommended. The discharge line safety valve is
installed in the cylinder head (Tu-Flo 550/750) or close to
the compressor discharge port and protects against over
pressurizing the compressor in the event of a discharge line freezeup.

So it is not even needed if not in cold weather.