Originally Posted by bugblatterbeast
I've been running 55w hids for about 7 years now. stock housings, no relays.
I measured the startup currents and they were no worse than what one would experience with a halogen bulbs. I haven't burned a stock lighting relay yet. considering that they are only $15 or so, I don't really care if I do burn one.
the measured temperature rise of the housing was less than with the stock bulbs. which makes sense given the bulb efficiency.
the only issue I've run into is the life time of the bulbs, which has been about 18 months on average. I just keep a spare on hand and order a new set when I use my spares. the bulbs have been less than $20 shipped to my door so I can't really complain.
What kit are you using?
The problem with a lot of "55w" HID kits is that they actually don't supply 50 or 55w to the bulb, closer to 40-45w.
The main concern when going without a relay harness for these situations isn't the stock relay, it's cooking the stock wiring. It varies from car to car, some need it, some don't. A relay harness is cheap insurance that helps the ballasts get clean and reliable power.
Also temperature rise may be less, but there is a fair chance that the UV output is much higher, raising the risk of damage.