you'll be better off getting a retro-fit kit for your headlights... I have Lexus GS HID's in my car.. in the 5th gens its not bad at all to install them... but the beam pattern really sucks compared to what it should be.

The Acura TL/CL use D2R bulbs... like most cars with reflector type HID's. They can be put in the 6th gen headlights, but its an odd task.

I definatly recomend a 9006 retro-fit kit that is made to be put in that particular housing. The D2R bulbs do not put the light source (the arc) in the exact position, as a 9006 kit will.

I recomend watching eBay, theres always good kits on there going for good prices. And stick with a reputable name brand... like Philips or Hella... Eagle Eye or Eaglite. Ive heard a lot of bad things about the ballasts in the other cheap brands.