I have a new VEMS unit, and it is reluctant to trigger on the output of a laptop soundcard using VEMSTune and play trigger.
My old units (serial no 557 and 326) work fine, but serial no 4371 doesn't really want to play. I have not checked it on a car yet, and I expect it will work fine. I am just curious.
IMHO for primary circuitry is unchanged. Might be pullup resistor value...
Secondary input has couple of little changes.
That would affect sensitivity... So is a potential change.
It works in the car, so it's not a problem.