hi bro, rmb me im the one with the derbi bike. bought a b2 from you 2weeks back. i must say it really improve my bike fuel consumption. i use to run about 24-26km per ltr. now i can say is about 30-32km per liter. it really work for my bike. also can i buy another b2 to use? will it work better? also i intend to change my exhaust pipe will it affect in anyway?