I noticed this morning when driving to work, a phenomenon that I experienced with the car, E6 GSR, in Munich over the winter period when the outside air temp was low, -10 to |PLS|5C approx. The temp this morning was about 10 Deg but quite a drop in temp from the previous evening. When I accelerated on boost the car seemed slugish and hesitant and the resonance from the exhaust sounded much louder than normal. This was not fuel cut syndrome but hesitation as if the plugs were breaking down. I changed the plugs 3000 miles ago. The car has been running fine up until this morning. This is really baffling me especially the noisey exhaust. Does anyone have an explanation for this strange problem?