most kits I have gotten I have bumped up the malt extract/hops ratio. this is merely a personal preference thing, so if you have gotten brew kits from them before and enjoyed them I would not advise tweaking the recipe. IF you are talking about like a flavor addition, then either vanilla beans(like the above post states^) or coffee. vanilla is a nice contrast, but coffee blends very well, especially if you use good coffee. Again, this is a personal preference of mine, so you might not like/enjoy as much as I do. But these are the ways I have used to spice up kits before I started putting my own recipes together