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Stone Exhaust

BMW M135i F20 F21 N55 valved cat-back exhaust AP504A

BMW M135i F20 F21 N55 valved cat-back exhaust AP504A

Regular price £2,584.32 GBP
Regular price £3,230.40 GBP Sale price £2,584.32 GBP
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Exhaust Valve System
Tailpipe Finish
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Direct-fit valved cat-back for F20 and F21 M135i models with the N55 engine - no coding, no adapters, no guesswork. OEM valve control integrates cleanly with your existing ECU.

  • OEM-style valve operation: quiet cruise, full aggressive note on demand
  • Zero drone thanks to tuned resonator and flow-optimised 7-axis pipework
  • One-piece construction with crisscross welded joints for strength and consistency
  • Includes Valvetronic remote (OBDII plug-and-play) for instant mode switching
  • Validated for UK roads and climate - fits RWD, xDrive and LCI variants

Not a daily-driver compromise or a track-only shoutbox - it’s a fast-road exhaust that works as hard as you do.

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