Description
Overview
The Flowmaster American Thunder Cat-back Exhaust System is engineered for the 2014-2019 Ford Fiesta ST equipped with the 1.6L engine, delivering the aggressive exterior sound and real performance gains that define the Flowmaster name. Built around the proven American Thunder series, this complete cat-back package pairs an Outlaw-series muffler with a matched chambered rear resonator to produce a bold, purposeful tone outside while keeping a moderate, pleasant interior sound at cruising speeds.
Every component is designed to work together. The system runs 2.50-inch mandrel-bent stainless steel tubing for smooth, unrestricted flow, connecting a specially designed hi-flow performance muffler and resonator that are tuned as a set to maximize power and refine the exhaust note. The result is a Fiesta ST that sounds the part and backs it up under the hood.
Sound & Performance
The Outlaw muffler measures 25.00 inches overall with a center inlet and center 2.50-inch outlet, while the rear chambered resonator (12.25″ long x 8.00″ wide x 4.00″ high) fine-tunes the character of the system. Together they deliver an aggressive-to-moderate sound level: assertive and unmistakable at throttle, yet civilized enough to live with day to day. The system is finished with a highly polished dual 3.00-inch exhaust tip featuring an embossed logo, adding a clean, finished look that matches the sound.
Fitment & Installation
This single tailpipe cat-back system is a direct fit for the 2014-2019 Ford Fiesta ST 1.6L. It mounts using all the factory hanger locations, so there’s no cutting or fabrication required for a straightforward bolt-on install. The kit ships complete with the muffler, silver-finished pipes, all necessary parts, hardware, and instructions, making it a project you can confidently tackle in your own garage.
Note that this is a kit-only configuration; the muffler is supplied as part of the complete system rather than as a standalone part number, and no heat shield is included. The system is CARB (California) compliant with Emission Code 5, so it’s a legal upgrade in emissions-restricted states.
Highlights
- Complete 2.50-inch mandrel-bent stainless steel tubing for maximum flow
- Matched Outlaw hi-flow muffler and chambered rear resonator tuned for power and tone
- Aggressive exterior sound with a moderate, pleasant interior tone while cruising
- Polished dual 3.00-inch exhaust tip with embossed logo
- Bolt-on install using factory hanger locations with included hardware and instructions
- CARB compliant and covered by Flowmaster’s Lifetime Limited Warranty
For Fiesta ST owners chasing a stronger, more exciting sound without sacrificing everyday drivability, the Flowmaster American Thunder cat-back is a purpose-built upgrade that looks, sounds, and performs the way a hot hatch should.
