To run double blades on a Zmaster do you need to get longer bolts or are the factory bolts long enough? I have a new Zmaster and it looks like it may take at least two washers between the blades to make them fit flush because of the cradle. Also what combination of blades works best on the Zmaster? The factory blades have low lift and don't seem to discharge the grass and leaves very well. Thanks for your input and opinions on the subject.