Out of curiosity I wrote to the folks at Cline, and they stated that 4 stroke muffler pressure works good, but 2 strokes needed crankcase pressure.
I am sure the Cline people are smart and know what works best with their product. However the measured pressure on two strokes appears to be in the same range as four strokes. Maybe volume is important with regulated pressure. Maybe higher pressures at lower RPM are important.
Bill