Everyone does know that anything about the stock bulb only creates less light right? There's a web page around that tells why.. It has something to do with the wavelength that the higher Kelvin lights emit not being effective to human vision.

 

this is HID and creates much more light then stock...

 

I think he is referring to the nature of the 7500K bulbs you have, and that even though it is HID, it still emits far less light than the stock 4100K bulbs.

 

Pigs can't roll on you for foglights unless they are brighter than your low beams. They can be whatever color you want them to be, although foglights are only functional in the fog when yellow or white. I've seen a Celica on the freeway with one pink foglight and one purple one. Without getting derogatory, it looked very "unmanly". Oh yes, and did I mention a teenage guy was driving it?

Ceterus paribus, a 4100K bulb is always brighter than a 5400K, 5800K, 6000K, 7000K, 7500K, 8000K, or 12000K bulb. The higher up you go in Kelvin, the more violet the color is. Violet light has a much larger wavelength than white or red on the other end of the visible spectrum. What a larger wavelength does is create more glare by bleeding out of the headlight at a wider angle. The glare is distracting to other motorists and often blinding as well. I'm looking at my Monster HTS-5000 MKII line conditioner with a red LED and a blue LED. The blue one is emitting a halo of light around it and the red one is not. Anyone with a blue LED can see the glare surrounding it. Same concept with HID. That is just one reason why blue light is a poor performer. The other being eye fatigue. Violet light is more energetic than white or red light and contains some ultraviolet content as well. Staring at it on the road for extended periods of time is much more tiring than staring at white light. Refer to beam pattern picture of 8000K HIDs in the other HID thread. Can you imagine driving around with that kind of lighting all night? I sure couldn't. Finally, because violet light is more energetic, it burns hotter. Ever touch a black light? Hot ain't it? This really is a non-issue, but higher Kelvin bulbs burn hotter, which stresses the headlight and all it's metal, plastic, and rubber parts more. Basically I'd much rather use a 4100K bulb, and if you want an aftermarket look, 6000K is about as high as I'd go.

For foglights, sure, go whatever color you want. Most people have no use for them anyway, so they become a cosmetic toy. If you like a light blue tone to your fogs, then no harm, no foul. Just don't use anything purple because it still creates blinding glare.

 

lex i agree with everything you said man...

my personal opinion is that these fogs aren't 7500k.. i knew this when buying them.. i think they are slightly overated and will know for sure when i get my 6000k phillips, 7500k should be much purpler right? well anyways from the pics i've seen my 7500k matches the 6000 exact.. and i took night pics (post soon) and you can CLEARLY see how much of an advantage it gives in close and sideways lighting.. this might not be important to some but to me it is.