I'v had the Ultras in my 2008 STA headlights for 4 years now. I finally had one of the bulbs go out, so I opted for the zXe bulbs. They are a little brighter, but the main difference I noticed was the clarity of the light emitted. They are VERY white with a hint of blue.... perfect, IMO. I just wish they made either the zXe or Ultra, in a H16 for my fog lights!