I fitted some Brisk plugs to mine, it ran much better than before
I guess any new plug would have made the same difference
Try Steptoe he had some platinum Deso plugs, which would be lots cheaper
Try this site. I fitted NGK Iriduim plugs to my single plug 2002 GS and they made a lot of difference re pick up and surging problems.www.spark-plugs.co.uk