Ordinary drivers will barely notice, but enthusiasts will spot the setup in an instant: big brakes, lightweight wheels and the lowered stance that mark this E46 M3 as a fellow traveler in the quest for better handling on the street and quicker lap times on the track.

As enthusiast drivers know, the M3’s high-revving 333-horsepower S54 six isn’t quite matched by either its brakes or its handling, and getting the most out of the car on the track requires upgrades to both. The trick, of course, is to make the car more capable without ruining its ride or reducing its driveability.

“It’s easy to mess up your car with the wrong parts,” says this M3’s owner, Matt Sweetwood. Sweetwood owns Unique Photo of Fairfield, New Jersey, and he uses his M3 regularly on the street, though not as his daily driver. (A mildly tuned E90 335i xDrive serves that purpose.) This car is really a toy, and Sweetwood plays with it on the streets of the Northeast and on tracks like New Jersey Motorsport Park, Lime Rock, Pocono, Summit Point and Watkins Glen, which he visits several times a year, most often with the BMW CCA. It’s Sweetwood’s third M3, following a pair of E36 M3s. Unlike those cars, this E46 has been modified for better performance…but only up to a point.

“I’ll only make modifications to the vehicle that won’t affect street use or comfort,” Sweetwood explains. “I won’t put in race seats or a roll bar, for instance.”

Nor will he go for big power in the form of forced induction. He installed an ESS supercharger on his previous daily driver, an E46 325xi sedan, but he doesn’t want to risk it in an M3 whose S54 engine is already high-strung. “I don’t feel comfortable doing that, as I question the longevity and street viability of such a modification.”

A bit more power, much better handling

Instead, he’s limited engine alterations to a PowerChip ECU upgrade, a Streamline SE air filter and an exhaust system modified with an Eisenmann 4 x 83mm stainless steel muffler joined to the stock catalyst with a Rasp Terminator connecting pipe. The latter uses a resonator on both connecting pipes, not just one like the stock system. The combination attains the perfect note of purpose and menace, at least to my taste. Rev this motor and people notice!

“It’s mainly a sound effect, but there’s a weight savings and a performance increase with it, too,” Sweetwood says.

Helping the M3 make the most of the available power is a Dinan 3.91:1 limited slip differential that replaces the stock 3.62:1 unit. “The differential makes the car faster off the line and makes sixth gear usable in the U.S., so that’s a street improvement,” he says.

A Dinan short-shifter provides crisp and precise shift action, while the removal of the stock clutch delay valve improves feel at the pedal—upgraded along with the rest of the foot controls to Ultimate Pedals.

Sweetwood also turned to Dinan for its Stage III suspension system. This consists of performance springs at all four corners, rebound-adjustable Koni struts and shocks, a 27mm front anti-roll bar (stock is 26mm) and camber plates that dial in more negative camber to reduce the M3’s inherent understeer.