Well, I don't have the light weight pulleys. I can't imagine they would make any real difference at all. They are pretty small items. The down side would be that you would have to do a lot of work to replace them. You would have to make sure your valve timing is correct, and you need a special tool to get the things off and then to install them. Your 2001 Sport has adjustable timing pulleys from the factory. That was a new feature in 2001. I think it was beneficial on older bikes to replace the factory pulleys with those aftermarket ones because they were easier to set the timing on. The older (prior to 2001) pulleys, needed an offset key to set valve timing. If you want to have less rotating mass for your engine, I would think a lightweight flywheel would give you more of a benefit for a lot less money and aggravation.