Does the AFlow Catted Section 1 for E46 get rid of the M3 rasp?

Yes. Active Autowerke states that the AFlow Catted Section 1 for E46 BMW M3 removes the raspy resonance the S54 produces at and above 4,000 rpm when performance headers are fitted with the factory Section 1. The rasp comes from engine sound harmonics in that rev range, and the redesigned section is built to stop it.

Do I need aftermarket headers for this Section 1?

Active Autowerke designed it for an E46 M3 that already has performance headers installed, and that is where it makes sense. With the factory headers, the stock Section 1 already flows well, so this part brings no meaningful gain and is not worth the outlay.

Will it cause a check engine light?

Active Autowerke states that it will not set a catalyst efficiency code. The post-catalyst oxygen sensors move into Section 1 behind the AFlow converters, the same arrangement BMW used on European M3s, and the supplied extension cables let the factory sensors reach their new positions. No tune is required.

Does it add horsepower?

No meaningful amount. Active Autowerke says power with its Section 1 is about the same as with the factory Section 1, which it considers a good result given that the exhaust now passes through two catalysts. The reason to buy it is sound quality and the converters, not a dyno number.

Is installation a bolt-on job?

Yes. The section uses the factory E46 M3 mounting points, so no cutting or welding is needed. The extra step is routing the post-catalyst oxygen sensors into their new ports with the supplied extension cables. Active Autowerke backs the part with a two-year warranty and free technical support.

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Description

Active Autowerke AFlow Catted Section 1 for E46 BMW M3

Active Autowerke’s AFlow Catted Section 1 for E46 BMW M3 is written for one specific car: an S54-powered M3 that already runs aftermarket performance headers. On that car the US factory Section 1, a straight-through pair of pipes with resonators built into one side, lets the S54 develop the raspy resonance it is known for at and above 4,000 rpm. Active Autowerke’s replacement pairs two Active AFlow catalysts with brushed 304 stainless pipework, quiets that rasp and holds power at the level of the factory section. It is a refinement and emissions part rather than a horsepower part, so an M3 on its factory headers gains nothing from it, while a header-equipped car gains a far more civil voice.

Design and Performance

Active Autowerke borrowed the layout BMW used on European M3s, moving the post-catalyst oxygen sensors into Section 1 behind the new converters. Extension cables are supplied so the factory sensors reach their new ports, and Active Autowerke states the result sets no catalyst efficiency code, with no performance tune required.

Features

Pair of EPA registered Active AFlow metallic catalysts
Post-catalyst oxygen sensor ports placed after the converters
Oxygen sensor extension cables included
Brushed finish on 100% 304 stainless steel
Bolts to the factory mounting points
Two-year warranty with free technical support

What’s Included

Section 1 with Active AFlow catalysts
Oxygen sensor extension cables

Applications

BMW M3: E46 | 2001-2006 | 3.2L S54

Notes

The AFlow Catted Section 1 for E46 is intended for M3s already fitted with aftermarket performance headers; on factory headers it offers no gain over the BMW Section 1
Power with the Active Autowerke Section 1 is about the same as with the factory Section 1, according to Active Autowerke
Also offered with GESI G-Sport catalysts as the GESI Catted Section 1 for E46 BMW M3

Frequently Asked Questions

Does the AFlow Catted Section 1 for E46 get rid of the M3 rasp? Yes. Active Autowerke states that the AFlow Catted Section 1 for E46 BMW M3 removes the raspy resonance the S54 produces at and above 4,000 rpm when performance headers are fitted with the factory Section 1. The rasp comes from engine sound harmonics in that rev range, and the redesigned section is built to stop it.
Do I need aftermarket headers for this Section 1? Active Autowerke designed it for an E46 M3 that already has performance headers installed, and that is where it makes sense. With the factory headers, the stock Section 1 already flows well, so this part brings no meaningful gain and is not worth the outlay.
Will it cause a check engine light? Active Autowerke states that it will not set a catalyst efficiency code. The post-catalyst oxygen sensors move into Section 1 behind the AFlow converters, the same arrangement BMW used on European M3s, and the supplied extension cables let the factory sensors reach their new positions. No tune is required.
Does it add horsepower? No meaningful amount. Active Autowerke says power with its Section 1 is about the same as with the factory Section 1, which it considers a good result given that the exhaust now passes through two catalysts. The reason to buy it is sound quality and the converters, not a dyno number.
Is installation a bolt-on job? Yes. The section uses the factory E46 M3 mounting points, so no cutting or welding is needed. The extra step is routing the post-catalyst oxygen sensors into their new ports with the supplied extension cables. Active Autowerke backs the part with a two-year warranty and free technical support.

About Active Autowerke

Active Autowerke was founded in Miami, Florida in 1981 by brothers Mike and Karl Hugh as a BMW service shop, and turned to performance in late 1995 when Karl, a University of Miami engineering graduate, led its first M3 and 325i turbo kits. Supercharger kits for the E36, E46 and E9X followed, and its Signature Equal Length mid-pipe is protected by US Patent 11248511 and European and UK Patent 3882441.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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Active Autowerke AFlow Catted Section 1 for E46 BMW M3 [11-010A]

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Active Autowerke AFlow Catted Section 1 for E46 BMW M3

Design and Performance

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About Active Autowerke

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