Why would a shorter boss make more top speed? I thought shorter bosses just start in a higher "gear". Because the belt can't go all the way down to the boss. If they are grinding the boss to remove a restricter then yes but a straight bosses length shouldn't affect top speed as the pulleys are moving closer together towards top speed not further apart. Also longer bosses allow the use of thicker belts with stock performance while a thicker belt with stock boss the belt tends to go out further on the vari due to the extra belt thickness.