I'm not certain what kit your looking at but I would have thought the kit comes with the required bushes for the antiroll bar to make sure it's of the correct size.
My rear antiroll bar came with clamps, bushes, drop links, rear antiroll bar - all of the correct size to fit as you would expect from a kit. The fronts came with uprated bushes of the correct size as well - so as to accommodate the size of the antiroll bar.
Also my golf was a 1.6 to begin with, I replaced my 1.6 antiroll bars with 25mm front and rear antiroll bars.