With the amount of people on here fitting mps4's to xdrives in the last couple of years, if they'd all had problems there would have been plenty of moaning but Ive not seen any.
I fitted mine in November to my 335d and not (touch wood) had any problems. As highlandpete mentions most people tend to get away with it and have no problems.
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F31 335d M Sport | Estoril Blue & CR | M Sport+ | Pro Nav | Comfort Pack | Adaptive M Sport suspension | Active Cruise
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