I could be wrong, just going off memory from a few years ago.
Check ADR 83/00 for the requirements.
Vehicle Standard (Australian Design Rule 83/00 - External Noise) 2005
Edit: This is how they are meant to test it
http://www.ntc.gov.au/filemedia/Repo...stSept2006.pdf
And to correct my previous comment. It is at 500m at 45 degrees at 4000rpm (for a 4cyl).
As for the maximum level, reading the ADR it is only 80dB now? Seems wrong and I should probably read it rather than skim through...
Further edit: Seems only the 2.5L WRX/STI's are subject to ADR83/00 (makes sense since the document is 2005) this gives a WRX a maximum of 85 dB and a STI 86 dB from the signature levels.