Anybody with a Kawi needs to know this... A guy on ZX-10 Forum that owns a shop did a dyno test on the Kawi brand filter, K&N, and BMC on a 2005 ZX10R. The K&N actually decreased hp from the Kawi filter by 2hp. The BMC was almost 2hp better than the Kawi filter. So spend the extra money on the BMC. Oh... and those of you who have bought the K&N and "felt the difference" it was just because you put in a fresh, clean filter. I just took my clean K&N out and replaced it with a BMC last night. The throttle response and growl from the intake is enough to notice the difference alone.