Thread: BT50 headlight upgrades?

If it's a standard H4 lens/unit then there are endless options for aftermarket LED/HID conversions.
May very well void WOF as mentioned above, since NZ govt seems to copy-paste australian legislation (ADR). But may also be no issue, depending who you get on the day.

Narva also sell "+50" to "+100" bulbs which have a different gas/fillament to provide more light.

Could pay to check out the loom and maybe run heavier gauge wiring and relays, since you may be getting considerable voltage drop with the old wiring.