Scan for codes. Otherwise its just a guessing game. Any independent BMW shop should be able to scan the car for a few bux.
BEST PRICES GUARANTEED - New N54 Performance Line Downpipes!!
JB4 **G5** On Sale - FREE Shipping Click Me - NEW JB4(N55) & DCI's $95.00
NEW F30 N20/N55 ER Downpipes and Chargepipes - BMS OCC (On Sale)