The stock 3700k that are in there would be just as bright if not slightly brighter. I know philips only have one white bulb that meets the ECE standard and that's the blue vision ultra becuase it uses the burner from the xtreme vision bulb to make more light but the blue 4300k coating takes away light so your left with a bulb putting out a standard amount of lumens but a whiter colour.
The original white bulbs (crysial vision and diamond vision) are off road use only (a nice way of saying illegal) becuase they don't meet the ECE standards for light output.
Also standard halogens are about 3700k, the xtreme vision and 50+ are about 3750-3900k and OEM Xenons are 4300k. The really bright white xenons you see in commodores are usually 6000k and are deemed illegal to some extent - one becuase they emit less light than a standard OEM xenon bulb but mostly because of the glare that is created using them inside reflector housings.
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