There is a new Philips 3rd Generation HIR bulb in the 9012 class (12.8V - 55W) that apparently is the tops when it comes to light output:
Originally Posted by Mr. Creosote
This 55-watt bulb is US DOT certified, with a nominal output of 1875 lumens, and is rated at approximately 25% more light from the same 55W bulb architecture. The 9012 series can be easily modded to fit into the 9006-class (HB4) base, in other words, we can use these in our 1-Gen foglights. Downside: they're expensive @ $32/ea.
I actually like this 9006 replacement bulb, and will probably pick up a set for my fogs.
Plus, they're $30 for the pair.
This is what they say about the bulb:
Experience safety in details!
NARVA provides the perfect solution in diffused lighting situations: NARVA Contrast+. It will help you tackle all possible weather conditions. Problems like low contrast, glare effects and low sharpness are solved.
» More intensive contrast » Extreme sharpness of details » German Technology (E1)
Contrast+ bulbs are coated by a newly-developed filter to improve contrast and detailed viewing for safe driving. The special coating acts as an indifference filter. It lets pass only certain sections of the spectrum, in essence filtering out the blues that cause glare. The effect of Contrast+ leads to more contrast and sharpness due to the behavior and function of human vision.
The effect is well known by skiers. The filter is comparable to the use of polarized glasses that improves contrast and sharpness of snowy hills. NARVA Contrast+ leads to greater safety and reliability in all situations.