I've installed Dr Pulley sliders in all 4 of the Kymco scooters I've owned ('09 People 150, '12 GTI 300I, '21 X-Town 300i ABS, '23 People S 150i ABS). I have always gone 1 to 1/2 grams lighter. It gives me a little better acceleration for around town driving. Pretty much negative impact on top end or mileage. Maybe not for everyone, but for an inexpensive performance gain, definitely a good way to go.