Crevier BMW in Orange County, California, is one of the bigger dealerships in the United States. They service and maintain our long-term BMWs for free. Actually, they do the same for everyone. Free maintenance is included with every new BMW sold. For four years or 50,000 miles, anyway. After that you're on your own.

Lucky for me, the M3 has proven to be an exceptionally hardy car with few, if any, real issues. It must have been a Thursday car, built in Regensburg by happy, clever Germans fully focused on the task at hand.

The M3's distinctive exhaust note made me smile the same way an air-cooled 911 does. Its metallic exhaust note was intoxicating. I say 'was' because I have since changed my mind. Unlike the 911, whose exhaust note is a byproduct of its engine configuration, the M3 makes its unique sound due to an unusually long tube just behind the catalyst, a design determined by emissions regs. That longish pipe vibrates at certain frequencies, hence the sound. By itself, BMW's straight six has a glorious tone, a voice we would release with the help of Magnaflow.

There are at least a half dozen companies that build M3 exhausts and most of them range from good to excellent. I chose Magnaflow based on its 20 years of experience, sound design and performance. I also got the opportunity to access its 30,000-square-foot tech center and 150,000-square-foot manufacturing facility. This operation is one of three in Southern California (there's one in Italy too), all of which employ state-of-the-art computer-controlled robotics. So, a serious player in the performance exhaust industry.

Magnaflow's E46 M3 exhaust is fabricated from T304 stainless steel stock and features mandrel-bent curves, clean welds and highly polished quad tips. The company has done a fabulous job minimizing its exhaust, shedding some 38 pounds in the process while adding a crossover pipe for extra scavenging. The system uses the factory hangers and standard slip-type compression fittings.

For reasons unknown (perhaps our M3 is special), the Magnaflow exhaust needed some persuasion to fit properly; a few minor shim devices (bolts) were used to clear certain sections. It's been my experience that most aftermarket exhausts need some help-provided it's nothing major this is easy to forgive. Such was the case here, especially after hearing its new-found voice.

While the stock exhaust is no shrinking violet, the Magnaflow system has a much more authoritative sound, something like distant thunder. Under load, the M3 now has a full-fledged roar, giving the sensation that it has somehow dislodged something from its throat. At cruising speeds, the car is slightly louder than before, but never annoying. There is, however, a substantial drone at 2450 rpm (I seldom see those revs during relaxed cruising, so it's not really an issue).

Ultimately, the exhaust is a fairly aggressive piece. It has changed the M3's demeanor considerably, not just in sound but in power delivery too. Dyno results yielded a solid 10-hp gain over the stock system. Listening to the menacing growl, it feels more like 30 hp. I guess that's a bonus.

The M3 emerged from its engine- and gear-oil change (Motul) washed and ready for action... sort of. A small contingent of Crevier people surrounded the car, ogling the wheels and brakes. As I got in to drive away, the tell-tale buzz of a dead battery scattered everyone. A sheepish service rep came out and informed me that it was time for a new one.

Given the on-and-off type of usage the M3 sees, a standard battery wasn't the best choice. I needed something able to retain big cranking amps after prolonged periods of inactivity. I needed an Optima Yellow Top battery.

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