Stage 1 Kits. Designed for motorcycles with a stock engine using the stock airbox, air filter, and stock or aftermarket pipe. Stage 1 kits are fully adjustable to allow the use of well-designed aftermarket pipes and K&N stock replacement air filters.
Stage 2 Kits. Designed for motorcycles with a stock or mildly modified engine using a well- designed stock or aftermarket pipe with a modified airbox and a stock or K&N replacement air filter. Stage 2 kits are designed for applications where individual air filters cannot be installed and for applications where airbox modifications improve overall engine performance.