Has anybody ever used these on their Tracer? I don't want to post a link in case it's not allowed but a simple Google search will help. 

Tia

I've had them on a YZ250, and will be getting one for the rear when I wear out my current 47T rear.
They look cool and work, but really it's just for the looks.  Nothing performance wise cutting out a breakfast here and there couldn't cure.