I’ve got Ifairings on a K4, fitment was excellent, as was the colour, I have not had a problem with them at all, completely satisfied with them.
One of my sons has got a K6, he has got Auctmart fairings on it, the fitment is not as good as the K4 but in saying that the K6 is a much more intricate design than the K4 so I guess it depends on what you are putting it on.
In both cases I hope you have got your OEM bolts because both brands leave a bit to be desired with their offerings for fasteners.