Best Ford Focus RS & ST Cat-Back Exhausts (2013-2018)

A cat-back exhaust is the single best-value way to wake up the sound of a Ford Focus RS or ST cat-back exhaust setup — and on the turbocharged 2.3L EcoBoost RS (350 hp) and 2.0L EcoBoost ST (252 hp), the right system shaves weight, adds a rally-bred rasp, and frees the turbo to spool without touching your tune. The Mk3 Focus RS and ST left the factory muted for pedestrians, not for enthusiasts. In our Tampa, FL shop we have installed dozens of these systems, and the difference between a good one and a droning headache comes down to muffler design and tip diameter. Below we break down the six best cat-back exhausts for the 2013-2018 Ford Focus ST and 2016-2018 Focus RS, with real specs, sound character, T304 vs T409 construction, and pricing from $815 to $1,865.

What Does a Cat-Back Exhaust Do on a Focus RS or ST?

A cat-back exhaust replaces everything from the catalytic converter back to the tips — the mid-pipe, resonator, muffler, and tailpipes — while leaving the emissions equipment in place, so it is street-legal in most states and requires no ECU tune. On a turbocharged engine like the Focus RS 2.3L or ST 2.0L EcoBoost, the factory exhaust is the biggest post-turbo restriction, and a larger 2.5-inch to 3-inch mandrel-bent system lowers backpressure after the turbine.

Be realistic about power: a cat-back alone typically frees roughly 5-10 wheel horsepower on these turbo Fords — the real turbo-spool and torque gains come from a downpipe and tune. What a cat-back does transform is sound, weight, and character. Swapping the heavy factory muffler for a straight-through design usually drops 10-18 lbs of unsprung tail weight and unlocks the aggressive, popping, rally-inspired note the Mk3 Focus is famous for. Choose your muffler and tip size to match how loud you actually want to live with day to day.

How We Ranked the Best Focus RS & ST Exhausts

We judged every system on four things that matter to a daily-driven hot hatch: sound character (aggressive vs. refined, and how much drone creeps in at 70 mph), construction (T304 stainless resists corrosion far better than T409 or aluminized steel), fitment (true bolt-on to factory hangers, correct RS-AWD vs. ST-FWD routing), and value. Prices below are live from our catalog and update automatically. Fitment note up front: RS systems fit the 2016-2018 all-wheel-drive 2.3L; ST systems fit the 2013-2018 front-wheel-drive 2.0L. They are not interchangeable because the rear chassis and hanger layout differ.

The 6 Best Ford Focus RS & ST Cat-Back Exhausts

Borla's ATAK ("Acoustically Tuned Applied Kinetics") is the loudest system in Borla's Focus RS lineup, built from premium T-304 austenitic stainless steel — the same corrosion-grade alloy used in marine hardware, and a clear step above the T-409 found on budget systems. It uses Borla's Polyphonic Harmonizer technology to layer multiple exhaust notes into a full, rich tone, and the 3-inch design produces zero drone in any gear at any speed. A sound-suppressing valve simulator keeps the check-engine light off while flowing freely. If you want the most aggressive, wannabe-rally-car snarl the RS can make, this is it.

The Ford Performance Active Sport system is the factory-engineered answer, and it is the only cat-back here with an electronically actuated valve. Open the butterfly for a full-bodied, aggressive tone under throttle; let it close for a quiet, drone-free highway cruise. Because it is designed by Ford Performance specifically for the RS, fit and tip alignment are flawless, and the polished stainless tips fill the factory diffuser cutouts cleanly. It is the priciest option here at $1,865, but for an owner who wants both a docile commute and a hooligan soundtrack on demand, valve control is worth it.

AWE Tuning splits its Focus RS lineup into Touring (resonated) and Track (non-resonated). The Touring Edition uses AWE's proprietary resonator tuning to kill cabin drone while still adding a noticeably richer, deeper voice than stock — it is the pick if you commute in the RS and value a headache-free highway run. Construction is mandrel-bent T304 stainless with your choice of Diamond Black or chrome-silver tips, and it is backed by AWE's lifetime exhaust warranty. Want it louder for less? The AWE Track Edition drops the resonators and lists for around $1,115.

aFe's Takeda series is the flow-first value play for the RS. It runs a full 3-inch mandrel-bent 304 stainless path — larger than most competitors — for a deep, mid-loud tone that leans muscular rather than raspy. The signature Blue Flame double-wall tips are a distinct look, and at $1,461 it undercuts the Borla and Ford Racing systems while still using aircraft-grade 304 SS. If you plan a downpipe and tune later, the 3-inch Takeda has the flow headroom to grow with the build.

For the 252-hp front-drive Focus ST, the Borla S-Type (part 140504) is our go-to. It is built from 2.5-inch CNC mandrel-bent T-304 stainless with patented multi-core, straight-through mufflers and dual 4.5-inch rolled/polished tips. The result is a mean deep growl at idle, an aggressive tone under throttle, and — critically for an ST — drone-free cruising. Like every Borla it carries the Million-Mile Warranty. At around $1,180 it is the sweet spot of sound, build quality, and price for the ST.

If you want the RS to sound bigger without four-figure spend, MBRP's 3-inch dual-outlet system is the value champion at $814.99. It is made from T409 stainless — more corrosion-prone than T304 but still weatherproof and half the price — and MBRP backs it with a limited lifetime warranty. Expect a louder, raspier note than the resonated systems, so it suits owners who prioritize volume and savings over a refined highway cruise.

Focus RS & ST Exhaust Comparison Table

RS vs ST: Why the Systems Are Not Interchangeable

The Mk3 Focus RS and ST share a chassis family but not an exhaust. The RS is all-wheel drive with a rear differential and driveshaft that force a different mid-pipe and hanger routing, and it runs the 2.3L EcoBoost with a factory dual-exit setup. The ST is front-wheel drive with the 2.0L EcoBoost and an open rear floor, so ST cat-backs (Borla 140504, Ford Racing M-5200-FST) are engineered for that layout. Always order by your exact model — an RS system will not bolt to an ST and vice versa. Fitment years to remember: RS is 2016-2018 (2017-2018 in North America), ST is 2013-2018.

Installation, Drone & What to Expect

All six systems are true bolt-on jobs that reuse the factory hangers and clamp to the stock catalytic converter or downpipe. In our Tampa shop, a Focus RS or ST cat-back typically takes about 60-90 minutes on a lift with basic hand tools — no cutting, welding, or ECU flash required. Because the catalytic converter stays in place, these systems keep the car emissions-friendly in most states. If drone (that low-frequency highway hum) is your main worry, choose a resonated system like the AWE Touring or a valve system like the Ford Racing Active. If you want maximum theater and do not mind more noise, the ATAK or MBRP will deliver. Pair any of them with a cold-air intake for a fuller induction note, or add a downpipe and tune later to actually raise output.