although as you said they didnt measure it, you probably had the ****** off cop who wanted to make his quota for the night and you unfortunately was there and had a "P" plate.. worst targets out,:( *feels bad man*
Remember, they inly need to "suspect" the item isnt road worthy, ie exhaust, tint etc... they dont have the equip nor skills to actualy road side test each thing. Sounds like you may have annoyed the police for them to screw you this hard...
I thought it was 90dB - going by what they mention in the EPA guide.
I dont know how I would have annoyed them, when I was just driving down Burwood HWY normally as I do without any hooning. Bloody ****** off as balls man.