PLM BMW M5 M8 S63R Downpipes Install Guide
By Aftermarket Car Parts -Private Label Mfg | Published: 2026-10-25
Category: How-to Guides
Step-by-step instructions for installing PLM catted downpipes on a BMW M5 or M8 F90. Includes torque specs, common mistakes, and performance expectations.
Quick answer
Installing PLM catted downpipes on your BMW M5 or M8 F90 is a weekend project that unlocks noticeable power gains while keeping your car emissions-compliant. Follow the steps below to avoid leaks and fitment issues.
Why choose catted downpipes
Catted downpipes like the PLM S63R design strike a balance between performance and legality. They reduce backpressure for improved exhaust flow and power, yet still pass emissions testing. This makes them a practical upgrade for daily-driven BMW M5 and M8 models.
What you’ll need
Before starting, gather a socket set (10mm, 13mm, 15mm), a torque wrench, penetrating oil, a jack and jack stands, and new exhaust gaskets. The PLM downpipes come with all necessary hardware, but replacing the OEM gaskets is recommended for a leak-free seal.
Installation steps
- Disconnect the battery and let the engine cool: Disconnect the negative battery terminal to prevent accidental starts. Allow the engine to cool completely to avoid burns. A hot engine can warp flanges; wait at least 2 hours after driving.
- Remove the OEM downpipes: Unbolt the factory downpipes from the exhaust manifolds and the mid-pipe. Use penetrating oil on rusted nuts. Support the pipes as you remove the last bolts. Mark the position of each bracket to make reinstallation easier. A common mistake is forgetting to disconnect the O2 sensor harness.
- Transfer the O2 sensors to the PLM downpipes: Carefully unscrew the oxygen sensors from the stock downpipes and install them into the threaded ports on the PLM pipes. Apply anti-seize compound to the threads. Overtightening can strip the port; hand-tighten then add a quarter turn with a wrench.
- Install the PLM catted downpipes: Position the new downpipes onto the manifold studs and the mid-pipe flange. Hand-tighten all fasteners first, then torque to spec (typically 35-40 ft-lb for the manifold nuts). Tighten in a crisscross pattern to ensure even pressure and prevent exhaust leaks.
- Reconnect the O2 sensors and check for clearance: Plug the O2 sensor connectors back into the wiring harness. Rotate the steering lock-to-lock and check that the downpipes do not contact the chassis or steering components. If you hear a rattle on a test drive, the pipes are likely contacting the body; loosen and reposition slightly.
- Reconnect the battery, start the engine, and check for leaks: Reconnect the battery, start the engine, and let it idle. Listen for hissing or ticking sounds at the flanges. Use a soapy water spray to check for exhaust leaks. A small leak at startup may seal after a heat cycle. If it persists, retorque the bolts.
Product facts
- PLM BMW M5 M8 S63R Catted Downpipes F90 2018+: The PLM BMW M5/M8 S63R Catted Downpipes for F90 201+ are designed to improve performance while remaining emissions compliant. You get a meaningful power boost without the hassle of switching parts for emissions testing, making this a true bolt-on upgrade for street use.
PLM BMW M5 M8 S63R Catted Downpipes F90 2018+
