Let your ride be heard like "thunder" with the Flowmaster American Thunder Exhaust Systems! This exhaust system was specially created for the enthusiast who wants their ride to be heard.The Flowmaster American Thunder is crafted from 16-gauge stainless steel for maximum durability ...Let your ride be heard like "thunder" with the Flowmaster American Thunder Exhaust Systems! This exhaust system was specially created for the enthusiast who wants their ride to be heard.The Flowmaster American Thunder is crafted from 16-gauge stainless steel for maximum durability, with every exhaust system mandrel bent for a smoother exhaust flow. It is designed with the latest technology that provides for passing power, enhanced acceleration, and better fuel economy.