Upgrading to the 06+ headlights...
The headlight P/N isn't here, but most don't order OEM lamps; although I'm sure you can find it in there somewhere
You will need headlights ($100-300), filler panels (~$38/each), H11 HID kit (most kits include 9006 type connectors so you can plug you stock harness in) ($40-300, though I would stay away from the $40), DRL wiring harnesses (~$28/each) if you want to use the 06' up DRLs & turn signals.
I have done the swap and IMO
pros -
-better cutoff due to the projectors (if you do the squirrel finder mod) so you don't get flashed, although some members claim they don't get flashed. Personally I went 3 months without getting flashed then all of the sudden everyone was flashing me and I had big rigs chasing me down the interstate with their brights on.
-cool look IMO with 4 DRL lights instead of 2
-updated look
cons-
-cutoff isn't as good as a retrofit (which from what I've seen usually runs ~$300-500 depending on if you do it yourself or send it to someone else)
-small triangle that looks a bit off if you don't use the '06 grille which requires modification to work with the 03-05 bumper
The retro will have the best cutoff and clearest light but will take more time and money.
I debated for a long time but went with the '06 upgrade because I like the '06 lamps better and it seemed easier to me.