I just installed a Xenonfactory 5000K HID kit in my girlfriends 02 EXT Friday night. Although I am not familiar with the SRX (aside from my fathers) I can try and answer a few questions. The 9006 (lowbeam) kit was not cheap, $520.00 shipped, but let me say after seeing the difference it was worth every penny. We plan on taking some pictures in the next few days and I'll post them up. I was really floored when I put my 02 Escalade next to her EXT with the lights on.......it looked like I had candles in my headlight housings!! Now on to the kit. One reason I purchased from them was the warranty they give (3 years). The other is power for the ballasts is drawn from the battery, rather than the stock wire harness. Each HID is seperate from the other, which helps trouble shooting could a problem exist. It took me about 2 hrs to install, with the hardest part trying to find an area to mount the ballast which has to be close to the HID bulb. I would say you have about 10 inches of wire to work with. I'll try and post the pics up here and also in the Escalade forum, let me know if you have anymore questions.
Regards
Walter