Craig, you've proved that you understand Ohm's law. However, you may want to check the NEC for sizing conductors. Table 310.16. 10 THHN (which is UV resistant) is actually rated at 40A at 90 degrees C. This table shows voltage from 0-2000v. It doesn't matter for A/C or D/C current. (see Table 310.13 for temperature ratings of conductors) 4 100W hella's at 12v is 33.3A. The alternator will give you over 14v, maybe a little less with the lights on. Either way a 10 will work fine. I doubt that you would consider the lights as being continuous duty since I don't know anyone that will leave them on for over 3 hours. I would be a little concerned about my battery and alternator at that point.
Koby, Is this stealthy enough?
Leigh, It's not bad. You have to pull off the visors and the "Oh Shit Handles". After that it's pretty easy to get at the factory rack bolt. I used a round bastard to notch the factory rack. I also used a little silicone before bolting that thing down. I've done this on 2 disco's and have never had a problem leaking. Notice Black and White. Believe me, your sunroofs will leak first.