Machine setup is critical in 125GP, it's one of the reasons why I love this class so much. The depth of learning is so high for a lightweight. You don't have to look far to see how setup worked super well for some and punished others over the past weekend of 125 racing at Ruapuna! I setup my bike up to give me the most confidence in my riding which generally means on the slightly soft and forgiving side. It might not be the fastest outright setting but it allows me to push my bike harder than I would be able to otherwise.
There's very few after market bits in my bike but one of the best improvements I've made so far is to have the gearbox super finished by the legends at Super Finishing Ltd. After a year of abuse, I had the gearbox out when I rebuilt the engine and the gears looked brand new. I couldn't believe it. I forgot just how slippery they were until I went to refit the things and had a hard time keeping it all in hand. The result is so good. When you can feel the friction reduction in your hand, imagine the improvement when they're spinning up at 13,000 engine RPM. The gearbox feels so silky smooth to shift through. When every horsepower and every km/hr added could mean a place, it's really worth getting done!
I hope the international 2 stroke racers who follow my racing see this post. I really think it's worth sending as much of your engine components over to get done. I can't rave about the results enough, this team knows their science! http://superfinishingnz.co.nz