Want to feel like Michael Andretti at Lagun Seca? Here's your ride. It's Autothority's 330RS, hot-rod 260-hp BMW coupe. It rides and handles like a racecar. Racecars, being more specialized than Neverland Ranch nose doctors, are usually noisy and clattery, and sometimes scary. The 330RS is this way too, and it's uncommonly fast. The "RS" is a clue to is character: it stands for the German "Rennsport" which means "racing sport."

The 330RS began as a 1994 325is. Its 2.5-liter six was bored and stroked to 3.0 liters, and its combustion chambers were coated with a heat-resistant ceramic. New cams of Autothority's own design were incorporated, along with other tuning. A throaty-sounding exhaust system with a header was installed for audio effect - it adds no power. And a recalibrated chip was added. The result is 260 hp - 20 more than an M3 - at 6500 rpm and 251 pound-feet of torque at 4300 rpm, all of it legal in California.

The 330RS gets to 60 mph in 5.4 seconds, only 0.1 second slower than BMW's fastest car, the 372-hp 850Csi. The 330RS is governor-limited to 145 mph, which is 8 mph faster than the M3's limit. But our test car costs $25,000 more than a $32,660 325is, or about the price of a 145-mph Infiniti Q45 sedan. Surprisingly, according to Paul Misencik of Autothority, 3-Series groupies who decide to modify their cars spend on average $20,000.

The 330RS's acceleration feels more thrilling than the $36,620 M3's. The engine is monstrously strong, and it pulls quickly to its rev limit, at which time the limiter quickly retards the timing and starts to shut off the fuel. Acceleration to this point is nearly fluid.

The $2200 wheel and tire package includes colossal 245/40-17 Dunlop SP Sport 8000s on eight-inch rims. The wheels, Anterral Type 101s, have no lip for wieghts, and a taped-on one flew off - which exlplains the shimmy we felt between 50 and 75 mph. Thicker anit-roll bars, stiff Bilstein shocks (but not the race tuned "Sport" versions), and lower, stiffer Eibach springs cost another $2900. The front control arm's rear mount bushings are unyielding urethane. Wedges added to the front hubs induce 1.5 degrees of negative camber. This keeps the outside edges of the tires from tucking under during high-load cornering. The normal fix for this condition, moving the struts inward at the top, would have required cutting the sheet-metal strut mounts.

When you're accelerating our of corners, the limited-slip differential - tightened from 25-percent lockup to 70 percent - causes the 330RS's rear end to slide quicker than an M3's would. But the smoothness of the slide makes it amusing rather than threatening.

Clunking noises emanate from the suspension on tight, bumpy corners. Vivid bump-steer, plus an on-center light spot in the steering, elevate your levels of concentration. Then in wide sweepers at 120 mph, the bump-steer arouses a lot of wander. The steering feels far too light at this speed, and the car rides hard enough that you can hear the steering shaft clacking in its rear-most bearing. Engine vibrations are transmitted into the cockpit through the stiffer suspension bushings. Stereo? We were so busy we forgot the car had one.

BMW's fluent and similarly swift M3 is available for about $20,000 less. Or you could leave the chasis of the 325is stock, bypass Autothority's enormous carbon-fiber front brakes, seats, and other changes, and just get the 3.0 -liter motor (and the limited-slip rear end and an M3 clutch) for $12,500, which sounds best to us.

Autothority figures 15 or so people will want the stiff race-car ride and twitchy handling of the 330RS. Consider the car's behavior as part of its price, or part of its payoff.

Vehicle Type: front-enging, rear-wheel-drive, 5-passenger, 2-door sedan

Price as tested: $57,618 (base price $45,160)

Engine type: DOHC 24 valve 6 in-line, iron block and aluminum head, Bosch Motronic-Autothority engine-control system with port fuel injection