greetings from Taiwan! I am a German living in Taiwan and distribute all Dr.Pulley items to Europe.
I have a special Dr.Pulley forumwww.drpulley.info/forum
Sorry, it is in German, but Google translate can help.
And I have an info blog www.pulley-scooter-tuning.blogspot.com with translation button.
Dr.Pulley recommends original weight (SiWi 600 28gr.) minus 10-15% So the best weight for you is 24gr. You will get a much better acceleration, no less maximun speed. Perhaps a little more gas consumption. The rolls are 49€ including all shipping to England. You can email me firstname.lastname@example.org