Getting a different sprocket - where from?

[dazzaboy]

where can i get a different sprocket for better acceleration and how many teeth shall i get? and how hard are they to change? thanks.

its on a 2001 curvy

[Berlin]

http://www.bandcexpress.co.uk/catalog/product/view/id/4396/s/s-p-sp4-jpg/category/242/

Or cheap steel ones on Ebay

C