Here's a link for a very very cheap GPZ500 I've seen for sale.
Its just a helmet cam, but you can hear the engine.could any of you experts have a listen to the vid..and tell me if it's a plum or sounds normal please?

http://youtu.be/x4stn1Vvj24

I've seen quite a few GPZ vids on youtube and they do seem to sound a bit rough at low revs