Had major overhaul of our 2011 335d ... NEW intake manifold, manual cleaning head intake ports, replaced other control parts and EGR cleaned thoroughly. Engine feels solid and smooth (as it always had)- except the evidence of the carbon built (rough idle, less than stellar acceleration) were gone. Have driven about 1,000+ miles since work and can report NO anomalies popping up as a result of workmanship. I would highly recommend Martin and his crew. Extraordinarily detailed and competent. They don't ever jack up prices with unnecessary replacement parts. (I've running original brakes - have them checked every service ... and in the crank case: LIquiMoly (4k intervals) - what they run in Germany).