well when your driving there will be air flowing over it cooling them a bit... How much hotter than the stock bulbs would you say? Best way is to get a laser temp gun or thermal camera if you have access and measure the delta.
2001 ZX3 2.0L Zetec-
Hatch Nation #42
Going through Rebuild See "The TICK Build Thread" for details (http://www.focusfanatics.com/forum/showthread.php?t=289168&referrerid=62897)