Wonding what info anyone can give me on this mod?

I understand that it's less rotating mass which will allow the motor to rev quicker.....or at least that's the theory behind it.

I'm wondering how much of a difference they make. What the stock ones weigh and on average what the lightweight ones weigh?

Any differences between the Bucci ones and the STM ones?

I see here that the Bucci ones come as pulleys and then rollers seperate, but that STM offers a pulley kit then sells the rollers seperate....

anyone have any info on this? I'd appreciate it!