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2019 Mercedes-AMG C63 S by CarBahn first drive: When more is actually better

How does one of the world's greatest Euro car tuners go about improving an almost perfect car?

The visual changes that CarBahn made to the C63 are subtle, but the performance changes aren't.
Drew Phillips/CarBahn Autosport

Modern performance cars are so unbelievably capable, yet they ask for minimal compromise in return. That's a great thing for sports car buyers. But a by-product of this is that it leaves aftermarket tuners very little on which to improve.

Take the Mercedes-AMG C63 S Coupe, for example. On paper, it's everything one could ask for in a fast-yet-quasi-practical-car. It's got more than 500 horsepower, sounds fantastic, is super comfortable, comes packed with myriad tech and convenience features and it's handsome to boot. What's to improve?

Steve Dinan recently started a new company called CarBahn Autoworks, and he's on a mission to find ways to make the already-lovely C63 S even better. If Steve's last name sounds familiar, it's because his old company Dinan Engineering was one of the most dominant forces in the BMW performance aftermarket and American road racing. Steve decided that there was more to life than fiddling with Bimmers, so CarBahn works on all kinds of things, even going as far as campaigning an Audi R8 GT4 in the  Michelin Pilot Challenge series. 

CarBahn's first modification replaces the standard C63's rolling stock with better wheels and tires. Steve Dinan could have added some fender flares to fit an off-the-shelf wheel and tire package, but he's not a man to half-ass something like this. Instead, he called the folks up at Forgeline and had them make a wheel to his exact specifications: One that's able to take full advantage of the space available under the C63's arches without worrying about rubbing or scraping.

The bespoke Forgeline wheels are 20-inches in diameter and a half-inch wider than stock.

Drew Phillips/CarBahn Autosport

The C63 S comes with fairly sizeable stock wheels, specifically 9-inches by 19-inches in the front and 10-inches by 19-inches in the rear. The bespoke Forgeline wheels from CarBahn add half an inch in width and a full inch in diameter, both front and back. The Forgelines come wrapped in Michelin Pilot Sport Cup R tires sized at 285/30R20 and 305/30R20, respectively. 

Of course, this was definitely not a cheap option, with the wheels costing around $10,000 for the set. Still, they look amazing, and the wider rubber helps with overall grip and handling.

From the wheels, the next step was the vehicle's suspension. Steve's approach here was also unconventional. Logic would say that he call up KW or Moton or JRZ and have them build a set of coilovers to his specifications. That would work, but then you'd lose the Mercedes' adaptive damping that, in stock form, makes the hardcore C63 S a tolerable daily driver, even on LA's crappy, broken roads.

Steve decided to keep the factory dampers, but had a set of progressive springs made that would lower the car slightly and take some of the motion out of the vehicle as it cornered, without making it overly stiff. Next, he set about adding adjustability into the suspension and taking rubber out of the various components. Usually, this would make a road car unbearable, transmitting every little shimmy and shake from lousy pavement to the interior of the car. Happily, Steve was able to find a way to do this without dramatically increasing the noise, vibration of hardness inside the vehicle and it involved using more race car components. Specifically, he changed essentially all of the bushings in the suspension to bearings, which allows the components to move more freely without deflecting.

Under the hood of the CarBahn C63 S, things again look pretty subtle save for the carbon airboxes, but that's because the larger twin-turbos are hidden.

Drew Phillips/CarBahn Autosport

On the road, the CarBahn C63 S has some of the most responsive steering turn-in I've felt in years. This tuned Mercedes feels very accurate and easy to place, with decent steering feel and a reassuring sense of linearity as you move the wheel. Driving in Comfort mode, the ride is just about perfect, with no additional creaks or rattles from the suspension -- a rarity in a heavily modified car.

While I find the suspension modifications to be super effective, the one thing I really would want is an axle-lift system. The lovely carbon fiber splitter that CarBahn whacked onto the front of the C63 is gorgeous, but LA is an unforgiving place with steep driveways. Driving this leaves me in near-constant panic, trying not to scrape the nose.

In stock form, the C63 S makes 503 horsepower, and while that's plenty, CarBahn couldn't just leave well enough alone. The 4.0-liter V8's stock turbos were swapped out for bigger ones, which not only increases power, but changes the engine's torque peak. Combined with a new engine control unit, the result is 674 horsepower and 666 pound-feet of torque, which in the C63, is simply absurd.

I've driven a handful of cars that make this kind of power, and the novelty and added responsibility get old pretty quickly. Cars like this are hard to enjoy even on a canyon road, simply because they're so fast, and while I'm sure the CarBahn C63 S would be extremely competent on a racetrack, I don't know if it would be my first choice for that either. In other words, the power bump seems sort of unnecessary -- cool as it is.

A 2019 Mercedes-AMG C63 S will set you back a not-insignificant $76,450 before options. The CarBahn GT-S kit seen on this car costs an additional $21,890, plus an extra $9,800 for the nifty wheel and tire package. CarBahn's work comes with a warranty that matches Mercedes' factory protection, too.

In the end, it would be hard for an average consumer to justify the cost of CarBahn's GT-S upgrade, despite its benefits. The C63 S is such a solid performer and a well-rounded vehicle right out of the factory that making any changes to AMG's work gets tough to justify. But CarBahn isn't building its cars for average consumers, and for people like Steve Dinan, good is the enemy of great, and great can become divine if pushed just a little harder, with bigger turbos.

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