The uk rhd versions have secondary cats at that place, but this is just a resonator (2x straight perforated tube with fibre).
That's where I've put my cats (which barely pass the MOT.... 0,2g/km HC)
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Z4 3.0i | ESS TS2+ supercharger | Quaife ATB LSD | Brembo/BMW performance BBK front/rear | Schrick FI cams | Schmiedmann headers+cats | Powerflex/strongflex PU bushings | Vibra-technics engine mounts | H&R anti rollbars | KW V3 coilovers/KW camber plates | Sachs race engineering clutch | tons of custom sh#t
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