Res delete

[Linden006RS]

is a resonator delete legal in NSW, not worried about police but the inspection required when registering car. 

[Honest Gaza]

I purchased my 2015 RS second hand (original owner had removed it).  I've never been questioned at Rego time.

[Darkrym]

Should never have issue with registration in NSW but maybe with the cops.

The two applicable NSW laws I could find are "Examples not requiring certification: Alternative exhaust systems that retain the original or equivalent emission control equipment eg headers, mufflers, complete exhaust systems." (https://www.nsw.gov.au/sites/default/files/2021-02/RMS-13.464-Light-vehicle-modifications-Vehicle-Standards-Information-No-6-November-2013.pdf)  and exhaust noise limit is "90 dB" (https://legislation.nsw.gov.au/view/whole/html/inforce/2024-09-09/sl-2017-0449#sch.1-sec.2)

Which a res delete passes the first law, but may have an issue with the second. I have not heard of them measuring dB at blue or pink slips but the cops might. This doc (https://www.ntc.gov.au/sites/default/files/assets/files/National Stationary Noise Test Procedures For In-Service Motor Vehicles .pdf) lays out how you test the decibels. it is complicated but from my interpretation. The distance of the microphone from the exhaust outlet shall be 500mm. ½ or ¾ Engine Speed at Maximum Power (ESMP) (½ where the ESMP is more than 5000 rpm). But where the ESMP for that engine has not been determined by the testing authority 5 cylinders or less is 4000 rpm (I cant find one for the megane but it may exist). The noise level shall be the maximum level measured between the stabilised test speed and when the throttle is swiftly returned to idle position, this test is then repeated till there are 3 results all within 1 db of each other. 

The problem here will be returning to idle from approx 4000rpm as without the res they love to back fire. Although if ever tested this will most likely be done out of sports mode and mine doesn't really back fire out of sports mode but my dads car does. I suspect you'll never have issues with the cops if your driving out of sports mode (I turn mine to normal if I see a cop) and not like a dickhead but if you do want to be careful you can download semi accurate apps on your phone which measure dB and do a quick check at 4000-5000rpm to idle.

If there are any mechanic around they might be able to tell you if the noise limits are ever checked in blue or pink slips. Also this is all my interpretation of the law there is a lawyer lurking on this forum who might have a more accurate understanding. 

Edited 10 September by Darkrym