Micoasters, this has worked for me in the past to keep a mower from dropping grass. Unzip the mod file, open the xml file for the mower (not the modDescxml) in notepad++, and go to the section that says <workAreas>. Find the line that says <mower dropWindrow="true" dropAreaIndex="2" /> and change "true" to "false. Then go to the section called <dropEffects> and comment out that entire section.