Custom Performance Single-Step E46 M3 / Z4M Header

Direct-fit, equal-length, stepped primary design headers designed to maximize mid-range torque

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If you've been waiting for a reasonably priced, high-quality stepped header for the BMW E46 M3 – your wait is over. The CPI Single-Step E46 M3 Header was designed to maximize midrange torque while maintaining strong peak horsepower. Dyno testing resulted in +15 horsepower at 7,500 RPM and +12 pound/feet of torque @ 4,300 RPM over stock (at the rear wheels).

  • 321 stainless steel (with satin finish instead of high polish)
  • fully TIG-welded joints
  • slightly oversized inlet flanges to minimize back-pulse
  • smooth transitions when pipes and flanges join - no edge, lip, or step to obstruct flow
  • 3-way merge collector
  • OE-style outlet flanges
  • proper bungs and locations for O2 and EGT sensors
Design & Pipe Sizes
Flanges: 1.56” (40mm) ID primary, slightly larger than 1.52” (38mm) ID exhaust port
Primary: single step lead pipe is 1.65” (42mm) OD steps to 1.78” (45mm) OD
Collector: 3-way merge pipe to 2.33” (60mm) OD collector pipe

Inlet Flange Note: longer studs to the cylinder head are required. The original BMW flange is very thin and the original studs are not long enough for this header (or nearly any aftermarket header). Our Header Install Kit below includes longer studs that are the correct length for these headers.

Notice of Emissions Non-Compliance. Removing, disabling, or altering emissions equipment on a pollution-controlled road vehicle is illegal. Installing devices or software that trick, disable, or modify emissions controls and monitors on a pollution-controlled road vehicle is also illegal. This product is sold only for racing, competition, track, or other off-road use. It's use is prohibited in any motor vehicle that is subject to emissions inspection or control. It is not legal for sale or use in California on any pollution-controlled motor vehicle.

BMW Fitments:

3 Series
E46 (99-05) > M3
Z Series
E85 / E86 Z4 (03-08) > Z4 M
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