My only advice to save a lot of mucking around is to go to an approved inspection centre rather than the DPI pits.....the approved inspection centres will only look at what's been written on the work order and nothing else and chances are they may not even have a db meter.

I had all sorts of headaches with my 99WRX years back when I had it.....every yellow I got came off just as fast with no probs.

I used a place in Rockingham on Dixon Rd but this was a few years back now but I had no dramas every time....not sure if they have become more strict now but its worth a go only cause when you go to the DPI they will not only look at what's on the work order but they will also go through the whole car looking for stuff.

PM me if you want more info