sounds like Kev's air temperature controller which fools the ECU into thinking it's a different temp than the ambient air temp and therefore instructs the ECU to richen the fuel/air mix. It's generally left at a 5 o'clock position to stop the bike being so lean on its mix. It's not the O2 mod which is a plug-n-play-no-fiddling device.

As for pops on the over run, this is normal and often stopped by blocking the AIS system. There is a sticky thread on how to do this.

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