Dinan Valved Cat-Back Exhaust with Polished Tips for G01 / G02 BMW X3 M40i and X4 M40i
The Dinan Valved Cat-Back Exhaust with Polished Tips replaces the factory dual-tip system on the G01 X3 M40i and G02 X4 M40i with an enlarged, straight single-pipe design and a Helmholtz-equipped muffler, cutting drone while opening up the B58’s voice. Factory valve control stays in place, so the system idles quiet and civil, then opens into a deeper, more aggressive tone under throttle. Four independent 3.75-inch polished tips replace the stock Y-tip setup with a genuine quad-tip layout, and the whole system bolts to the factory mounting points with no cutting or welding.
Features
- Larger 83mm piping for increased flow, up from the stock size
- Factory resonator and collector removed for a bigger, more open exhaust note
- Genuine quad-tip layout: four independent, double-walled polished tips with a laser-engraved Dinan logo, not a Y-tip splitter
- Helmholtz-equipped muffler tuned to reduce cabin drone
- Factory valve functionality retained for a quiet cruise or an aggressive, throttle-matched tone
- 100% T304 stainless steel construction, TIG welded with no hydroformed pipe
- Direct bolt-on installation at the factory mounting points; no cutting or welding
Specifications
- Body and Pipe Material: T304 stainless steel, TIG welded
- Pipe Diameter: 83mm (vs. 80mm stock)
- Tip Configuration: Quad, 3.75-inch (95mm), double-walled, polished finish
- System Weight: 53 lbs (7 lbs lighter than the stock system)
- Peak Gains: +6 HP at 6600 RPM, +5 lb-ft of torque at 6600 RPM
- Installation Time: 2.3 hours, no cutting or welding
- Muffler Type: Helmholtz-equipped, valved
What’s Included
- Quad exhaust tips, polished
- Mounting hardware
- Valve componentry
- Installation clamps
- Hangers
Applications
- BMW X3 M40i: G01 | 2018-2025 | B58
- BMW X4 M40i: G02 | 2018-2025 | B58
Notes
- This SKU is the polished-tip finish. Dinan also offers a black ceramic-coated tip version under part number D660-0099-BLK.
- Pairs with an aftermarket valve remote for manual override of the valve, sold separately
Frequently Asked Questions
Will the Dinan Valved Cat-Back Exhaust fit both pre-LCI and LCI X3 M40i and X4 M40i models? Yes. It ships with mounting hardware and valve componentry for both the pre-facelift and facelift (LCI) G01 X3 M40i and G02 X4 M40i, so one part number covers the full 2018-2025 model range.
How much power does this exhaust add? On the dyno, the Dinan Valved Cat-Back Exhaust added up to 6 horsepower and 5 lb-ft of torque at 6600 RPM; the bigger difference is the reduced backpressure from the larger 83mm piping and the open single-pipe design.
Does the exhaust stay quiet with the valves closed? Yes. Factory valve functionality is retained, so the system defaults to a refined, quiet tone for daily driving and opens into a louder, more aggressive note under throttle or in Sport mode.
Is installation difficult? No. The system bolts directly to the factory mounting points with no cutting or welding required, and Dinan lists roughly 2.3 hours of labor for a shop install.
What are the Dinan Valved Cat-Back Exhaust tips made from? The tips are double-walled stainless steel with a polished finish and a laser-engraved Dinan logo, mounted as four independent outlets instead of a Y-tip splitter; a black ceramic-coated tip version is available under a separate part number.
Is this exhaust street legal? Yes. Dinan rates this system as legal for emissions-controlled street use as well as off-road and competition use, and factory valve control keeps sound within a comfortable daily-driving range when closed.
About Dinan
Founded in 1979, Dinan is North America’s leading BMW tuner, developing, manufacturing, and marketing a full line of high-performance products for BMW, MINI, and Mercedes-Benz. Dinan works through a nationwide network of Authorized Dinan Performance Centers, including select BMW dealerships and independent BMW service and performance shops. The company’s warranty program, introduced in 1996 with BMW of North America’s cooperation, matches BMW’s new car warranty and covers Dinan enhancements and the vehicle itself for up to 4 years or 50,000 miles. That coverage lets BMW owners add real performance without risking their factory warranty. Automotive publications have tested Dinan-enhanced BMWs against some of the world’s most exotic sports cars for three decades, and the results consistently hold up. Despite that performance, Dinan BMWs keep the reliability and everyday civility BMW owners expect. The product line spans engine, driveline, and chassis components across the full BMW lineup, covering acceleration, cornering, and stopping power. Every Authorized Dinan Performance Center can help build anything from a single upgrade to a complete Dinan BMW.
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