i went to an exaust sound off on sunday with the rollaboys(perth rice club)
The guys there had a decibel meter but i dont think they where using it properlly because to measure an exaust sound wouldn't you hold it close to the ground not up above the car?
anyway i got 104.7 DB some guy with a v6 vt ute got 124db it was stock (engine) with a 2 1/2 strit threw muffler & cat.
A susuki got the lowest with 93
It was good for a bit of a gigle there was a v8 soarer that got 117.