Revs reading taken at:
In the case of an engine that has a manufacturer’s engine speed maximum power (ESMP) that is known to the LVV certifier, 75% of that figure;
The sound is measured at 45degrees from the muffler exit at a distance of 500mm.
The result of an exhaust noise emission test of a low volume vehicle must be calculated from the average of three separate and consecutive measurements, each of which must be within 2 dBA of each other.
in the case of an MA, MB, MC, MD1, MD2, or NA-class production vehicle that was manufactured before 1 January 1985, 95 dBA
in the case of an MA, MB, MC, MD1, MD2, or NA-class production vehicle that was manufactured on or after 1 January 1985:
(i) if first registered in New Zealand before 1 June 2008, 95 dBA; or
(ii) if first registered in New Zealand on or after 1 June 2008, 90 dBA.
A factor of 4 dBA may be added to the decibel level specified in 2.9(1), in order to compensate for the increased background noise caused by the close proximity of the engine to the exhaust outlet, in the case of a low volume vehicle, other than a motor-cycle, that has either:
(a) the engine positioned to the rear of the driver; or
(b) the exhaust outlet positioned within 1.5 metres (5 feet) of the engine.
Here is the document that covers exhaust noise emissions.[/url]