For the person looking for a complete Header-back dual exhaust system with an aggressive tone. With easy fit in mind, Flowmaster's American Thunder systems include specially-selected Super 44 mufflers to make your vehicle come alive. These header-back dual exhaust systems use 409S stainless steel tubing (backed by our 10-year warranty!) and a durable H-pipe design that delivers improved throttle response, power and mileage. 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.