I used them for about an hour without any heat issue, but that is a good idea to keep an eye on any issues from heat buildup causing anything to melt, but I don't think it should be an issue, since Xenon bulbs should run cooler than a comparable halogen from what I've read and these are 2.5 watt lower than the factory bulbs. If I would've had a temperature gun I would have checked, so we could gotten a comparison. These xenon bulbs were 35 watt as compared to the 37.5 watt halogen bulb. Yes, they were a direct fit from the factory bulb and all you did was remove your halogen bulb and put the xenon bulb in the socket and then hook the original bulb harness to the ballast that comes with xenon kit and finally hookup the final two wires. It took maybe 5 minutes to install the kit. I bought them on Ebay and they were like $21.00 for the full kit. The brand was Xentec and I got them for the 894 bulb that they replaced. The only downside to the xenon bulbs is they take about 5 to 10 seconds to warmup to their full brightness, so when you first turn on they'll be dim for about 2 seconds and then gradually warmup to full brightness in about 10 seconds. Also, I think I would've gone with 4300K vs the 5000k light temp. The lower the number the more actual light it will seem to produce. The higher the number the whiter the light will become.