I've read many threads about headlight flickering. Unfortunately some say it's the bulb and some say the igniter. I've noticed only a few times that the passenger bulb will flicker for a second. The few times I've noticed was when braking while going downhill. This is is probably a coincidence but I figured I should mention it. My assumption is the bulb is going. Is there a way to test it is the bulb before I order one? Should I get an oem bulb or is an aftermarket bulb just as good?

 

In my experience with HID headlights the ballasts (igniters) ALWAYS die before the bulb. If the bulb is flickering just sometimes then it's probably not the bulb, if it was the bulb I would imagine the problem would always be there and not be intermittent. If you can try swapping the ballasts and see if the problem goes away.
I'm not 100% sure on which bulbs you should get, I've always gone with cheap aftermarket bulbs but recently have been questioning that decision.

When the light starts to flicker see if you can poke your head around where the ballast would be and listen for a ticking/grinding noise. It almost sound like a relay fault (really fast ticking) but a bit more electrical sounding (hence the grinding). Tough to describe but you'll know it if you hear it. If you can hear that then the problem is in your ballast.

 

It's most likely your bulb. However, you can test by swapping the bulbs and see if the flicker follows the bulb or stays with the ballast.

How many miles are on the car? It's probably time for an upgrade anyway.

 

106k. What would be a good upgrade in terms of bulbs?

I've read some threads about swapping bulbs. It doesn't look like a very fun job!

 

I believe the OEM bulb is made by GE its a D2S 35W bulb.

 

OSRAM CBI is the best bulb available.

 

Are they close to factory in terms of temperature? I don't like bluish looking aftermarket hid lights. I had aftermarket 4300k bulbs in my accord and they were great. I started with 5k and I didn't like how blue they were.