Well 2 days after I initially posted this, the right headlight went out completely. I had my bulbs from amazon here the following day. I replaced both the L & R bulbs. The sylvania D1S bulbs seem to be exactly the same as the Philips bulbs that were in the car to begin with.
Changing the bulbs turned out to be a big pain in the ass. Not as much as some cars I've had to deal with however.(1st gen Acura TL for example - have to completely remove the bumper assembly to remove the headlamp assembly on one side)
So basically what I'm saying is if anyone's bulbs go out, these ones from amazon will work just fine. No need to spend well over $200 a piece at the dealer.
2010 Chevrolet Avalanche LT (Imperial Blue Metallic)
2008 BMW X5 3.0i (Alpine White)
2001 Suzuki SV650S (Candy Blue Metallic)
2004 BMW X3 3.0i (Mystic Blue Metallic)
2001 Pontiac Grand Prix GT (Galaxy Silver Metallic)