Hi all. A mate of mine has an '09 Yamaha R1 and he has just fitted a set of Yoshimura cans and mid pipe (eliminates cat). Since fitting the system the bike apears to run slightly lean. Some popping on deceleration and the smell of a lean running engine. Normally i would fit a power commander or have the stock ECU re-mapped however the bike is fitted with an oxeygen sensor. Isn't the job of the oxeygen sensor to tell the ECU if the engine is running lean or rich. So therefore the bke shouldn't need re-calibrating. Anyone have some insight?