Depend on what rules you use. Around here we use AKRA rules, so the only real difference between a box stock and clone is the pipe, jetting, air filter, flywheel and clutch. Clones use big pipe, bigger jets, aluminum flywheel, air filter and adapter, and a disc clutch. Box stock uses weinie pipe, stock airbox, steel flywheel and stock timing, shoe/drum clutch, and stock jetting.