Bought the 2016 Downtown 300i last summer. 6 year old machine with 1400 miles on it. Last fall ordered a Malossi belt and DR Pulley 15 gram sliders with some concern for the age of the belt not the miles. Even with no problems showing with the original belt decided to do the change and not worry about summer riding. The Malossi belt measured and compared to the orginal I took off. Original belt had minor wear and no cracks or signs of concern. The rollers were just starting to develop some flat spots, at 5400 miles. Sanded the glaze off the clutch pads and went back together easy.
Have to say if it wasn't for the Downtown 300 having a tachometer I would not know any difference with the DR Sliders. Not exactly sure what weight the original rollers are, I had heard 16 grams, and the tach does show I think a bit more rpm at take-off and with cruising about at 30 to 40 mph. Not a bad thing, it seems a little smoother using a touch more rpm.
Conclusion . If the DR Pulley sliders last longer, which I have heard they will, The Sliders are an OK choice.
Looking at my old beam torque wrench, noted it was made in Taiwan. How appropriate for my Made in Taiwan Kymco.
Art