Focus ST 2013+ Flowmaster American Thunder™ Stainless Steel Single Cat-Back Exhaust System

American Thunder gives you exactly the sound that is promised by the name of the series. The exhaust sound of the American Thunder system has become a symbol of American power that is recognized all over the world. American Thunder is the most popular of the Flowmaster exhaust systems, enhancing power, torque, throttle response and mileage for automobile enthusiasts all over the world.

All Flowmaster exhaust systems give the same improvement of performance. All Flowmaster exhaust systems produce a beautiful deep performance tone. Choosing between the five different exhaust systems is not a technical decision – it is all up to your personal taste. It's A Sound Decision™. The racing origin is evident in every Flowmaster exhaust system. All the five series of systems are tuned for maximum performance. They differ in technology and tuning, and thus in tone and character, giving you a performance engine sound to your personal liking.

Flowmaster exhaust systems employ two unique technologies, the patented Delta Flow and the Laminar Flow. They give different characters of sound and can be tuned to achieve the desired exhaust note. Flowmaster Exhaust System Technology is so versatile and gives such a high degree of control that it is used both by racers, who want maximum power, and by the U.S. Air Force in Stealth applications, where maximum silence and minimum heat emissions are prime considerations.

Be it for a domestic or import truck, SUV, off-road warrior, daily driver, muscle car, euro-spec cruiser or sport compact vehicle, Flowmaster technicians personally hand select the right muffler, tubing size, resonator, and tip to make the process easy for you. Best of all, Flowmaster stainless steel exhaust systems are covered by a Limited Lifetime Warranty; ensuring that your exhaust will last as long as you own your vehicle. If you choose aluminized steel products, Flowmaster backs them up with a 3-year warranty.

Flowmaster® has its roots in solving the engine noise problems encountered by California racers in the 1980s. In 1983 Flowmaster's founder, Ray Flugger, created his first patented design of racing silencers, which dampened noise with minimal loss of power. Ray attached handles to ease carrying the square shaped race mufflers through the race pits, and the mufflers became known as the "suitcase mufflers." Today, the innovative Flowmaster mufflers are the result of years of development with top race engine builders, thousands of hours of dyno research and "real-world" on-track testing.