Howzit Yuri, welcome.

Have a look here : http://www.nsr250.net/forums/viewtopic.php?t=6218

Very hard to find the SP's here in SA since most people dont know what they are...

I had a 21SP race bike and now I have a 28SP. It depends on what you are going to use it for, if its just for the collection go for the 28 if you can find one....