[Kevan]

NSR Mosler AW. Can't go smaller with the tyres or bigger with the spur so it'll have to be the pinion. Didn't want to do that really though.

Perhaps a driving course would be in order then 

Why can't you fit a bigger spur?

1 tooth on the pinion is approximately 3 on the spur (depending on ratio).

You'd get a much bigger improvement getting a SW pod for it, none of our club race and lap records are held by AW, we are also non mag on routed track.