I believe an IS300 has D2R bulbs. You should use D2S bulbs. You can get rebased h.i.d bulbs on ebay with Lexus Denso ballasts for about $300. I wouldn't get the Mc culloch or Philips kits. I have the rebased bulbs in my corolla with Denso ballasts. They work great. I have had the philips kit which is considered one of the better kits. The ballasts cannot be turned off and on repeatedtly. But yeah, search and do some homework