The factory exhaust system on the 2013-2016 Focus STs doesn't sound particularly bad, but it doesn't sound as awesome as it could. Not to mention, the factory system can hold you back from making more power when your start stacking on some go-fast modifications. All of our Focus ST Cat-Back exhaust kits come from high-quality manufacturers like Magnaflow, Flowmaster, and Borla so that you get perfect fitment, excellent quality, and a great sound the first time. These kits use highly-efficient tubing and specially-designed mufflers and resonators to improve exhaust flow and produce throaty, loud roars. All of these cat-back kits are direct bolt-on replacements for your stock kit and even reuse the tip provisions in your lower valance. Once you have a Focus ST exhaust picked out, check out our intakes and tuners or our suspension upgrades.