Is it making this noise under load at low RPM?
At idle, the injectors are noisy, but if you get a noise under load at low RPM, it probably is pinging. Is the noise the same as the injector noise at idle?
As its a HSV there should be a knock sensor, which should prevent pinging and you shouldn't be able to hear it.
Adding premium ULP or an octane booster should lessen the effect if its pinging.
The manuals suggest testing the knock sensor by tapping the block with a hammer and watching the idle speed drop. Check that this is the way to test it first before you try it.