here it is:

Examples of minor (owner certified) modifications are:
􀂄 Engine changes where the capacity increase is less than 15% above the maximum size engine available for the
vehicle (providing no major structural modifications are necessary and where noise and/or exhaust emission
ADRs apply, all standard equipment such as carburettors, exhaust systems, exhaust gas recirculating valves,
oxygen sensors and catalytic convertors relating to noise and emission control are retained and operate
correctly).
􀂄 The fitting of a proprietary sunroof (if the modifications are of a minor nature only).
􀂄 Fitting a ‘package’ available as optional equipment for the vehicle (eg front disc brakes, power steering, alternative
transmission and bucket or bench seats).
􀂄 Additional lighting eg fog & driving lights.
􀂄 Alternative wheels and tyres within the owner certified limits set by the Authority (see Vehicle Standards
Information Sheet No. 9 Guidelines for alternative wheels & tyres).
􀂄 Fitting of handling enhancing suspension components such as roll stabiliser bars and up-rated shock absorbers.
Major modifications which fall outside the category of minor (owner certified) modifications require submission of
certification by an RTA recognised engineering signatory. This is usually in the form of an Engineering certificate
prepared by the signatory.