Heaps of people keep asking about mods and WOF issues etc, so once again here is the info....
For Questions Regarding WOF's or CERT's these following links may be usefull to you :
This document has been prepared by the LTSA for the use of vehicle inspectors and inspecting organisations to aid in achieving correct and consistent standards of in service inspection and certification (WoF & CoF):
http://www.landtransport.govt.nz/certifiers/virm-in-service/index.html
You'll need Adobe Acrobat to download and read each chapter, which you ought to be able to find here
Basicaly this means that your car must comply with everything listed on that page to get a WOF. If that page says you need a LVV certification, here is the LVVTA website which has good information, frequently asked questions, where your closest certifier is and alot more:
http://www.lvvta.org.nz/newindex3.html