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Mercedes-Benz C-Class and AMG: Performance Modifications

The Mercedes-Benz C-Class w204 is a well equipped vehicle from the factory, but there are many that want to take its performance to the next level. Thanks to performance shops across the world, there are quite a few options available to achieve this.

By Weston Chadwick - May 11, 2015

This article applies to the Mercedes-Benz C-Class and AMG w204 (2007-2014).

Performance modifications bring immediate satisfaction to the driver. They take the vehicle's factory performance levels (horsepower, torque, handling stopping distance) and raise them up—in some cases up to 100%. It is now possible to have super car like performance in your C-Class. Below are some of the more common modifications for your Mercedes-Benz C-Class and AMG.

Engine Control Unit (ECU) Tuning

DIY Cost – $700-$1,300+ May only include the hardware/not the dyno tuning

Professional Cost – $1,000-$1,700 (dyno tuning included)

Skill Level – Easy; plug the tool into the OBD-II port, and load the E.C.U. Map.

ECU tuning is critical to have your engine and transmission operating properly. You will see the best horsepower/torque gains when you have your vehicle properly dyno tuned after any modifications are made. You may also see improvements to your fuel economy and shift timing. Recommended for its performance.

Intake

DIY Cost– $100-$200

Professional Cost– $300 for parts and labor

Skill Level – Easy; this modification requires only basic hand tools, and can be done in less than 30 minutes.

Performance air intakes allow air to flow into your engine more efficiently, increasing power. The piping is generally made from a stainless steel (versus the factory rubber), which helps the intake air temperatures remain lower.

While the turbocharged C250 may benefit the most from aftermarket intakes, the naturally-aspirated C300/C350 and C63AMG see a massive benefit in aural department. Aftermarket intakes open up the induction sound produced by the engine, and sound aggressive under throttle. Recommended for its increase in power.

Wheels and Tires

DIY Cost – $2,500-$5,000

Professional Cost – $200-$300 to mount and balance the tires

Skill Level – Easy; only requires the removal of five lug nuts after mounting/balancing.

Performance wheels and tires reduce un-sprung weight, and increase grip with the road. They are designed to take the abuse that comes with driving a car on the track, such as extreme braking and cornering. They also add a personal touch to your vehicle.

Many C63 owners specifically lament the fact that the original equipment wheels are quite narrow, given the weight of the car and the power of the engine. Wider wheels and tires alleviate the issues by offering increased grip. Recommended for its grip on the road.

Brakes

DIY Cost – $1,000-$5,000+ for a complete braking kit

Professional Cost – $400-$600 for labor plus parts

Skill Level – Moderate; requires a large assortment of hand tools. There is plenty of access to most fasteners.

Performance brakes allow you to stop your vehicle in a shorter distance. They also dissipate heat faster. This is important during prolonged periods of heavy braking.

Many people opt to upgrade their front brakes only because they do the majority of the vehicle's braking. There are "plug and play" kits available from vendors like Brembo and RacingBrake that allow for easy installation. Recommended for its shorter stopping distance.

Headers and Exhaust

DIY Cost – $400-$1,200 for headers; $1,000-$2,000 for exhaust

Professional Cost – $400-$500 for labor

Skill Level – Hard for headers; requires a large array of hand tools. Access is limited to some fasteners.

Moderate for exhaust; requires an array of hand tools. Most fasteners are easily accessible.

A performance exhaust does a couple of great things for the Mercedes C-Class. It provides a sportier tone, and it helps the engine remove exhaust gases easier, which increases power. It also weighs less than the factory exhaust system.

For the C250 models, with their inline 4-cylinder, turbocharged engine, the most common exhaust component to be replaced is the downpipe. This is the piping immediately after the turbocharger and manifold. By replacing this with a higher-flowing aftermarket part, turbo lag is decreased and boost pressures can be turned up.

For the C300/C350, the "cat-back" is the most common upgrade. This component, as the name suggests, is the piping after the rear catalytic converters. This is a plug and play option that greatly affects the tone of the exhaust.

For the C63 AMG, the most power proven exhaust upgrade is in the headers. This is the primary the piping coming off of the engine. A properly designed pair of headers better scavenges the exhaust gases sent out of the engine, and greatly improves flow as well as performance. Recommended for its looks and increase in power.

Coilovers


DIY Cost – $1,500-$10,000

Professional Cost – $400-$600 for labor

Skill Level – Moderate; a large assortment of hand tools is required. Access to the coilovers is limited at times. Proper vehicle alignment requires an alignment rack.

Performance coilovers improve your vehicles handling. They also allow you to adjust your ride height and dampening levels. This allows you to fine your vehicles comfort and performance levels for the street as well as track. As previously stated, most off the shelf coilovers offer height and rebound adjustment. More expensive coilovers will also offer compression adjustment, camber and caster adjustment.

Put simply, compression adjustment controls the rate at which the shock absorber will compress (i.e. the downward stroke). Rebound controls the rate at which the shock pushes back up and reaches its neutral position.

Camber and caster are alignment angles that affect the static tilt of the tire (camber), and the dynamic camber change of the tire as you turn the steering wheel (caster). Generally speaking, you want as much caster as the adjustment will offer because this improves stability, and aids the vehicle when cornering. You want to optimize camber based on how the car is used, with more "negative" camber often being needed at the race track. This means that the tire is tilted further inboard to help the tire wear and cornering at the limit. Recommended for its improved handling.

Limited Slip Differential

DIY Cost – $1,000-$3,000

Professional Cost –$300-$500 for labor

Skill Level – Hard; requires removal of the exhaust system and differential.

Limited slip differentials (LSD) improve acceleration both from a stop and while cornering. They balance the torque output between the wheels receiving power from the driveshaft. When one tire begins to loose traction, the LSD senses the speed of the that tire is increasing and more power is applied to the the tire with traction. Recommended for its improved acceleration.

Pro Tip

For C63 AMG owners, Alpha Performance makes a performance package that includes engine tuning and a full exhaust system. Horsepower gains of 110 have been achieved with this package.

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