Rear of engine, or bank 2 and bank 1 catalytic converter fits all 128i and convertible models with N52 2.5L 6cyl from 2008 to 2013. Direct fit unit interchanges with OE unit. Collector portion is near identical copy of the original unit to ensure proper flow and performance. Unit has provisions for both factory O2 sensors. OBDII converter core insures long life and low emissions.