The part number is listed in a chart on 7-9 in the manual. Order it from Yamaha. Doug Dubach was the first one I'm aware of to make this recommendation, and Yamaha themselves went to the NFLR in '07. Specific jetting isn't really an element of the Zip-Ty mod. Ummm...Going to a new needle is only for 8k ft and above according to Dubach. Not sure why you'd make this suggestion when I don't ride that high of an elevation.