[stephen low]

Bobby Vic requirement for our test is that the noise meter be level in height with exhaust outlet, 600mm away and 45 degrees outwards. But this is for a standard rear facing outlet. Still reckon you'll have a similiar requirement particularly not measured directly in front to eliminate other created noise effects.

In fact my tips arc down towards the ground and although I was asked to only rev to 3500- 3600 when strictly it should have been 3950 rpm, I achieved 89dBA or 1 dB under the limit.

I tried making progressively smaller orfice plates mounted just after the cats but even with a 25mm hole was still getting low 90's readings at my correct revs.

I ended up going with the attitiude that if I needed to add hot dogs or similar just to get over the line I might argue my way out of that at the test else I'd get them installed and passed and they'd have dropped off afterwards.

Merv was nearly right at the start, for every 3 dBA increase it is a doubling of sound power. And A weighting replicates the human hearing and is what the test is done as.

What the WA limit?

Cheers