If you are looking to upgrade your Focus ST with a complete Header-back dual exhaust system that has an aggressive tone, Flowmaster has the system for you. With easy fit in mind, these systems are mandrel bent for maximum performance and include specially selected mufflers. American Thunder systems deliver a moderate to aggressive interior and exterior tone and are suited to the enthusiast who wants their performance to be heard. Like all Flowmaster systems, the benefits include improved throttle response, power and mileage. Designed for an easy fit, these systems include all necessary parts and hardware for easy installation.
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