I’ve just put in this Xtreme kit into the NC using the 4300k bulbs that equate to the OEM bulb type.
http://www.kbcarstuff.com/HID-Kits-s/216.htm It comes with dual ballasts, dual wiring harness with relays, fuses, Phillips bulbs, etc, etc.
I decided to go for a quality kit and pay a little more as I’ve read a few problem reports on the cheaper Chinese kits being faulty straight from purchase. With the AUD being at 1.08 to the USD the end price for the Xtreme kit was AU$241.10 delivered.
The NC uses an H7 bulb in a projector style headlamp, but a word of warning about these kits,
you need to get the H7 bulb adaptor http://www.kbcarstuff.com/OEM-Bulb-Adaptors-s/125.htm I didn’t and the postage was very expensive.
I read reports on Miata.net about how people installed them into the NC as the access to the lamps are VERY restricted. Most US enthusiasts removed the nose cone and then the headlight assembly to gain access to the left lamp. I decided that this was too time consuming so I removed the three bolts holding the fuse box/ECU and move it just enough to get my contorted hand into the back of the light assembly. After three attempts to get the HID bulb aligned correctly taking about 15 minutes each attempt, it would probably have been easier to use the US method. Attempt number four will be tonight. I’m going to modify the adaptor as it sits a little high on the supplied bulb in the NC housing.
The right lamp is easier to get to and sits OK in the housing but I’ll probably modify that to match the left side. The beam cuts off at the same level as the original halogen bulb and doesn’t appear to have any flaring when I view it from the front of the car.
I’ll update the report when I get the left side sorted.