These engines, like the 1200, are very noisy. Fantastic power, torque and drive-ability but totally suck in the agricultural mechanical sound they make. What i am hearing is not pre-ignition or detonation. My engine makes similar sounds and is possibly valve/tappet clatter and maybe more internal stuff like clutch & gearbox.mine is 7000km on odo and 10 months old.
the sound is only heard while the engine is warm and in the idle
Interestingly my lhs cylinder seems louder & worse than the rhs. Must be a BMW thing.