4-Inch Catless Downpipe

The IPOS B46 True 4-Inch Catless Downpipe is engineered to maximize exhaust flow for the B46 engine. Featuring a full 4-inch diameter until after the flex pipe, this downpipe offers enhanced performance potential. It is designed to bolt directly to your stock exhaust system, with the option to be easily modified for a true 4-inch custom turbo-back exhaust by cutting and welding after the flex pipe. Installation is simplified by the inclusion of a free 3-inch v-band clamp, designed to overcome the common issues associated with seized OEM clamps and poor-design exhaust leaks. The downpipe itself is constructed to be the largest currently available on the market. Optional additions include Heatshield Products Lava Exhaust Wrap to help keep the engine bay cooler and a Downpipe to Turbo Gasket, which is required for any downpipe swap. This downpipe is specifically designed to fit the stock Gen 1 B46 and Gen 2 B46TU exhaust systems, covering models such as the 230i, 330i, 430i, 220i, 320i, and 420i. It is explicitly stated that this downpipe **will not fit on a B48** engine. The manufacturer notes that most B4x engines in North America are B46 variants, and advises customers to contact them if unsure about compatibility.