This is definitely worth getting, installed on my 2012 Ninja 250r and wow! No more hesitation, great throttle response and more power in the low to mid rpm's.
Stage 2 Jet Kits
Intended for motorcycles with a stock or mildly tuned engine using a well designed aftermarket pipe with a modified airbox and a stock replacement air filter. Stage 2 kits are designed for applications where individual filters cannot be installed and for applications where airbox modification improves the engine's performance. In most cases power increases of approximately 8% can be achieved.