Short answer: Motorsport authority card required.
Longer Answer form
http://www.lvvta.org.nz/newindex6.html:
Dear Certed,
I have a Racepro bucket seat in my VR-4, but I'm wanting to fit a Sabelt harness seat belt as well. Is that legal or not? One mate told me it's sweet if you have the factory seat belts still installed, and another mate told me you can't have them unless you use the car for racing. I use the car at the Night Drags, but I'm not sure if that counts?
Please help, Thanks, Anton.
Hi Anton,
The simple answer is no, you can't have a full-harness belt in a road-going vehicle (yeah, yeah, I know it seems crazy too, but there are reasons why LTSA won't allow it, which I won't get into here).
There's only two ways you can have a full-harness seatbelt:
1. The Low Volume Standards allow for full-harness belts, but only in single-row seat scratch-built cars like custom-built sports cars, kit cars, and hot rods.
2. The only way to have a full-harness belt in a production road car is with a Motorsport NZ Authority Card. This doesn't provide for import drag cars though.
However, there is an alternative Authority Card system being developed for vehicles that compete in drag racing competition classes. It will solve the problem for many - it's just taking a while to get it to the top of the to-do pile. We'll give you that info when it's in place.
All the best, Old Hoon.