Cant seem to find too much on this. My car came with a set of those Sonar Spyder headlight housings... and the factory HID system doesnt seem to work. Checked the relays and fuses... they dont kick over. Can I just convert them to LED?
How would I go about doing that? ...or do I need to start buying HID parts?

Stock HID's are of the type "D2S" . you can find LED kits to fit if you search for that. I advice to find a good picture of a D2S bulb and compare it to what you got to make sure the previous owner didn't change something.
If all is good, you'll need a D2S to led conversion kit, to change out the hid ballasts to what's needed for the LED's.

edit: might want to watch this before deciding to change.

That guys laundry room is all rigged up. He need to fix his house before wasting money on headlight parts lol

I think it's just an unfinished basement, pretty common, you should see mine.

He does have an impressive collection of laundry detergent containers though!

On a separate note, it drives me OCD crazy when people call an LED assembly (LED module + Driver) a "LED bulb"

Bulb!!11!!!one!!!

Please don't install LED where proper HID belongs. The G35 comes with a really Good HID projector and the sedan has a good modern reflector.

If your car came stock with Halogens, leave it halogen.

The way Halogens reflect light, can't effectively put light on the road with HID or LED. It's just science. Google HIDPlanet for official studies.

DO NOT PUT LED IN A G35 IT IS NOT AN LED REFLECTOR OR PROJECTOR. YOU LOSE DOWN ROAD VISION WITH LED.

If your car was designed to run on gasoline do not put diesel in it.

People cause fires to their headlights all the time with aftermarket HID and LED products. Stay far away.

They aren’t even factory housings... or bulbs, apparently. These are D2R.

Spider headlights unfortunately aren't of the best quality.

Here (pic) is an example of LED in an HID projector housing where it was designed for HID. The bottom shows the factory D2S bulb while the top shows drop in LED.

I would recommend considering replacing those with stock headlights. Spider is about looks, and not about seeing at night.

definitely stick with oem. I switched to LED for one night and big mistake. Good for other parts but not headlights.

Grabbed some bulbs with everyones suggestions... still no go with lights though ):
How do I go about testing the ballasts? Ive got a multimeter, but Im pretty sure I remember these things being like 23KV... and dont wanna blow apart a really decent Fluke multimeter, lol.
The bulbs I got ARE questionable, theyre donors out of a wrecked Maxima, but match what I had.

Clarification: They match the D2S that I should have had stock.
The ones that were in there (Non functioning) when I bought the car were D2R.
The ones I grabbed from the Maxi were D2S.

None work so far.
Guy with the Maxi said they SHOULD work, as the last that car ran (year ago) they worked, but his son may have swapped them into one of his other Nissans. (They were free, so it was whatever)

They make HID testers but they're really expensive, that's why most folks just try swapping lamps (or replacing) and if it doesn't work (and you have proper voltage on line side of the ballast) then just replace the ballast.

Don't use your fluke or you will he opening the case to replace the little fuse inside it next to the battery

It's the strike voltage that causes the problem, strike can be up to 25kvdc but operating voltage is MUCH lower, <1000vdc

HID systems is something that I do not like to cheap out on. A new set of quality bulbs with some refurbished ballasts from eBay should not run you more than 120$ for a new pair. May seem steep but the car is more than 10 years old and an oem setup should last you another 10 years. Using used replacements or w/e just creates more work when they fail again.