Is there a performance related reason to consider an open primary or is it strictly looks?

06 FXSTSI

 

The 3" open primary is stronger than stock and also quicker since you loose the compensator sprocket on the main shaft. a lot of drag bikes use an open primary. A closed 1 1/2" primary doesn't really gain you anything and you need to allow cooler air in to the primary because heat is the biggest enemy of a belt for longevity. My opinion they also look better(3" open).

 

Thanks.