Direct answer
If the vehicle is registered in New South Wales, Transport for NSW is the agency that tells you how to record a modification, when an inspection is required, and which certification scheme applies. VSB 14 remains the national technical text. Do not treat a Victorian approved-modifications list as a NSW permission slip.
What to open first
Open the TfNSW page on changes to a registered vehicle. From there, follow their links to vehicle standards, the Vehicle Safety Compliance Certification Scheme (the name NSW uses for much significant-modification certification), and any information sheets that match the system you are changing — lighting, exhaust, tyres, identity. If a URL has moved, start at nsw.gov.au and search the same phrases. We will not invent a form number that the agency can rename.
Description changes
The VSB 14 introduction uses engine number and colour as examples of description changes that require contact with the registration authority. NSW registration records those fields. If your job will change them, tell TfNSW before you assume the work is “just mechanical”.
Inspections
NSW uses authorised inspection schemes for roadworthiness and for some modification pathways. The inspector in front of the car applies the instrument in force that day. A passed inspection last year is not a standing exemption for a new combination of wheels and springs.
Next
Return to the state rules hub or to getting engineer sign-off. Check with TfNSW or a certifier they recognise before you modify the vehicle.