• Milltek Secondary Catalyst Bypass | BMW G8X M3 M4

Milltek Secondary Catalyst Bypass | BMW G8X M3 M4

$1,228.36
$1,228.36
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Milltek Axle Back Secondary Catalyst Bypass system for BMW G8X M3 and M4. Direct fitment 102mm single mid-pipe with X-pipe configuration. Non-resonated design for closed-course and track use. Connects to either OE axle back (SSXBM1342) or Milltek Cat-Back Axle Back (SSXBM1341).

Mandrel-bent T304L stainless steel construction with hand-finished welds. Removes secondary catalyst restrictions post-turbocharger for improved turbo efficiency and mid-range response. Engineered to work seamlessly with both OEM and Milltek exhaust systems. Uses OE mounting points and hangers—no modification required.

  • Fits BMW G8X M3 (S58 engine) with OE or Milltek axle-back systems
  • Fits BMW G8X M4 (S58 engine) with OE or Milltek axle-back systems
  • Non-resonated: optimized for track and closed-course driving
  • 102mm bore mandrel-bent X-pipe design
  • T304L stainless, TUV tested for durability

Designed and manufactured in the UK with 40+ years of performance exhaust heritage. Tested at the Nurburgring.

Milltek Secondary Catalyst Bypass | BMW G8X M3 M4

$1,228.36

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    Really pleased with the quality for the price. The product felt premium, worked perfectly out of the box, and was well packaged.

    Jamie Carter
    Manchester, England

Can I return a part after it has been installed?

Generally, installed or used performance parts cannot be returned. We strongly recommend verifying vehicle fitment and inspecting the product before installation.

Can I cancel my order after it has been placed?

We begin processing orders as quickly as possible. If you need to cancel, contact us immediately. Once an order has entered fulfillment, been submitted to a supplier, or shipped, cancellation may no longer be possible.

Will this part fit my vehicle?

Fitment varies by year, make, model, trim, engine, and drivetrain. Use our vehicle fitment information to confirm compatibility. If you're unsure, contact us with your VIN and we'll help verify fitment before you order.

How do I know if this is the right upgrade for my build?

Not every upgrade makes sense for every vehicle or build. Tell us your vehicle, current modifications, and performance goals, and we'll help determine whether this product is a good fit.

Are the products you sell authentic?

Yes. We source products through established manufacturers and authorized distribution channels. We do not sell counterfeit or imitation performance parts.

Is professional installation recommended?

For most performance components, yes. Proper installation is critical for fitment, reliability, and performance. Some products may also require specialized tools, programming, tuning, or additional supporting modifications.