Rogue Engineering Billet Aluminum Exhaust Support Brace - E46 M3 | E9X M3The Rogue Engineering Exhaust Support Bracket replaces the steel OEM bracket 18 21 1 436 309 with a CNC'd 6061 ACQ machined replacement. Often times the original brackets on vehicles become rusty and bent. This allowed RE an opportunity to create a lighter version while making it from a more corrosion resistant material. NOTE: These are sold individually. E46 vehicles require TWO exhaust braces while E9X M3 and E88 128i 135i only use ONE brace.