I just recently purchased an "02" Busa. The dude I got it from put a 4 into 1 Yosh TRS exhaust on it, and changed the sproket to get more low end torque. The bike has its stock filter, and to the best of my knoledge it has nothing done to the OBC. What do I need to do? If you realy get on the bike hard sometimes I get small back fire. I am realy thinking of changing the sprocket back the the OE one, and purchasing a K&N. It is real touchy when cruising around town. Please give me some feed back.