Just a thought on the airbox- they are very restrictive on letting enough air into the engine for max power. And usually expensive if you can find both halves and the filter element. For less than $15 you can get a 28-29mm cone filter with metal mesh element that clamps on carb body. And you should notice a little better top speed if all else is set-up and working properly. The only downside is that you can't use the cute side covers if you have them as they snap into the OEM airbox.