The new Solas Concord YV-CD-13/20 blows away the performance of your stock impeller! Large blade area and superior hub design deliver increased acceleration and top speed. This 13/20 variable pitch impeller works great with stock through Stage 2 modifications. NOTE: Designed for use with Yamaha FZR/FZS SVHO & FX SVHO models (Stock - Stage 2 modifications).