The NGP bulbs can be found from a reputable U.S. source and with better pricing.
Is the Vosla HIR2 +120 better than either the Philips XtremeVision +150 HIR2 or NightGuide Platinum +130 HIR2?
Sorry, by "better" I meant output.This is really more than one question, because the answer depends what "better" means. Better output? (By how much...by enough to be worthwhile costwise...by enough to be worthwhile with the shorter lifetime?).
Yeah, I've got the upgrades already, trimming tabs off here and there. And they work great.Meh. Why bother? You can already get bulbs for those types, better than anything Philips has (Toshiba 9011 for the 9005, and either a good H9 or Stern's H11 +140 with no blue tint). Or do you want these for testing and quantification?
Those Fog Vision were designed for fog use only applications. That is why the H11 and 9006 types they sell only have a yellow band in the coil region and not full body yellow. (Since H11 and 9006 can be used in a headlamp and fog lamps). With the yellow color band on H11/9006 the total integrated color is still in the SAE white box. (Threading the needle as you say) Concern in my opinion was that people would put them into the headlamps instead of fog lamps. Therefore if they did it will still be legal. If they were full yellow coat then they would fall out of the SAE white box. The other's are full yellow such at the 880, 881, 9145 and H8's because they were never used in a forward lighting application.Fashion fad, pure and simple. There's no other real reason for it (just a bunch of made-up cockamammy baloney about "whiter light" and "closer to natural sunlight" and all the rest of the nonsense claims).
Technically there's no reason why not yellow. There are yellow-coated bulbs on the market, like these (a type applicable only to fog lamps) and these (a type also applicable to headlamps, so has to have "plausible deniability" about white/yellow) and these (no "plausible deniability" from this brand, and LOL @ "2500K" claim).