High-quality Catless Downpipe for BMW G30, G31 540i, 540iX models with B58 engine. Our 4.5-inch design minimizes exhaust gas restrictions as much as possible, improving both the sound and the power output of the B58 engine. Does not fit models with GPF / OPF. FITS THESE BMW MODELS: BMW 5 Series: G30, G31 [2017-2020] 540i (250kw / 340hp) – B58 540iX (250kw / 340hp) – B58 Note: If your model is not listed here, look for it under another product. If you cannot find your model anywhere, contact us for assistance. SPECIFICATION: • Quality stainless steel (SS304) • Downpipe diameter: 4.5″ (114mm) • Flange to turbine diameter: 134mm • Connection to exhaust (stock): 80mm • Two sockets for lambda (oxygen) sensors OEM reference part numbers: 18 32 8 631 625, 18328631625, 8631625, 18 32 8 684 788, 18328684788, 8684788, 18 32 8 652 180, 18328652180, 8652180