its quite simple actually.cheap ones give crappy results.
but it also depends on the intensity...like 6000k ones are white-ish sumtimes muddy like u mentioned.the 8000k ones are the clear ones.if im not mistaken.
Since there has been some sharing on other non jap ecu tunnings, perhaps if there is anybody interested in getting their jap aftermarket ecu tuned, you might be interested in this.