Stroker's kit works quite well.
Actually reducing trail does encourage a headshake from a geometrical standpoint as there is less self centering effect. Some outfits do have a slight slow speed headshake. Hands on bars does wonders.
I would still encourage you to check everything over closely as mentioned earlier. What you DO NOT want is a high speed wobble...this needs to be avoided at all costs. Some of the items mentioned in my earlier post can be the source of this so checking things out closely is still very important.