S58 Downpipes - BMW G8X / G87

Purpose-built downpipes for the S58 platform, fabricated in-house to replace the restrictive factory units and let the turbos breathe the way they were meant to.

The factory downpipes choke the S58 right off the turbine housing. Ours hold a full 3.0-inch cross-section from the outlet down, with a gradual taper only where it meets the mid-pipe, so flow is never pinched where it matters most. The result is reduced backpressure, faster spool, and a noticeably more aggressive exhaust note.

Each pipe is hand-formed from T304 stainless steel and joined with fully back-purged TIG welds for clean internal flow and long-term durability under heat. Mandrel-bent tubing maintains cross-section through every bend, and smooth-radius routing keeps turbulence down where the factory design compromises.

200-Cell Catted or Non-Catted. The catted version runs high-flow 200-cell catalytic sections to cut emissions and tame volume for daily driving while still flowing far better than stock. Non-Catted deletes the catalytic sections entirely for maximum flow and the most aggressive tone. Non-catted is intended for off-road or race use and may not be emissions-compliant in all regions, so confirm local regulations before ordering.

Heat-Wrapped or Bare. Both configurations are available wrapped in high-temperature thermal barrier or left as bare stainless. In a bay as tight as the S58's, the wrap's biggest job is heat management: it pulls a meaningful amount of radiant heat off everything packed around the turbos, including wiring, sensors, and the intake charge sitting nearby. Lower under-hood temps mean more consistent power on repeat pulls and less heat soak into surrounding components. Keeping that heat in the pipe also helps maintain exhaust velocity and scavenging downstream of the turbo. Bare stainless is the choice if you want the raw look under the hood or plan to run your own coating.

Direct bolt-on with no cutting or modification required. Retains factory sensor locations and pairs with the INR Mach-1 mid-section for the full system.

Specs

• Material: T304 stainless steel
• Construction: full back-purged TIG welds
• Tubing: 3.0-inch mandrel-bent, smooth-radius bends
• Configurations: 200-cell catted / Non-catted
• Finish options: Heat-wrapped (high-temp thermal barrier) / Bare stainless
• Hardware: all mounting hardware included
• Fitment: 2021+ BMW G80/G82 M3/M4 (RWD and xDrive, incl. Competition), 2023+ BMW G87 M2.