Thinking of upgrading my stock mount to one of these two kits....I do occasional XC racing here locally in WV and KY....any thoughts (postive/negitive) on these?

 

Is the 330 a bolt-on, or do you need to bore the cases? I know for sure the 310 is a bolt-on kit. If the 330 does need the cases bored, that will add to the cost vs. the 310. Also, I have heard the 330 loses some top-end over-rev without really adding much bottom-end when compared to the 310. For harescrambles and GNCC, the 310 is more than enough. I know a guy who races GNCC with a bone stock 250R including the factory 34PJ carb and kicks some butt in the Jr (25 and over) class and pulls some very respectable overall finishes. What kind of suspension mods do you have? You are much better off putting the money in some fully adjustable triple rate shocks up front if you don't have them already.