The Great S197 Exhaust Debate
Walk into any Mustang meet and ask which exhaust brand is best. You'll get three answers: Flowmaster diehards swear by the classic American muscle rumble. Borla fans love the aggressive tone with minimal drone. Corsa owners brag about zero drone and premium build quality.
So which one is actually best? We spent $1,200 buying and testing all three on the same 2012 GT with a stock 5.0L Coyote engine. Here's everything you need to know.
Testing Methodology
Same car (2012 GT, bone stock except for exhaust), same dyno (Dynojet), same day (to eliminate weather variables). We also measured cabin noise at idle, cruise (70 mph), and wide-open throttle using a calibrated decibel meter.
Exhaust systems tested:
- Flowmaster American Thunder — $379
- Borla S-Type — $449
- Corsa Sport — $499
Sound Comparison: The Most Important Factor
Let's be real: 90% of people buy an exhaust for sound, not the 5-8 whp gain. So we're starting here.
Flowmaster American Thunder
Sound character: Deep, aggressive V8 rumble with classic muscle car tone. Lots of low-end growl. Sounds angry at idle, mean at WOT.
Drone level (1-10): 6/10 — Noticeable drone between 1,800-2,200 RPM (highway cruising range). Not unbearable, but you'll hear it on long trips. After 45 minutes of highway driving, it gets tiring.
Volume: 78 dB at idle, 95 dB at WOT, 82 dB at 70 mph cruise
Best for: Weekend warriors who don't daily drive or anyone who loves old-school muscle car sound. If you grew up drooling over '60s Mustangs, this is your exhaust.
Borla S-Type
Sound character: Aggressive but refined. Less low-end rumble than Flowmaster, more high-RPM scream. Clean tone with no rasp or tinny notes. Sounds modern and performance-oriented.
Drone level (1-10): 3/10 — Minimal drone thanks to Borla's XR-1 multicore technology. You'll hear a slight hum around 2,000 RPM, but it's barely noticeable. Daily drivable.
Volume: 75 dB at idle, 93 dB at WOT, 78 dB at 70 mph cruise
Best for: Daily drivers who want aggressive sound without the highway headache. This is the "Goldilocks" exhaust — loud when you want it, quiet when you don't.
Corsa Sport
Sound character: Deep and throaty with zero rasp. The most refined sound of the three. Sounds like a luxury sports car — think BMW M3, not NASCAR stock car.
Drone level (1-10): 1/10 — This is Corsa's signature feature. Their patented Reflective Sound Cancellation (RSC) technology actually eliminates drone frequencies. You can cruise at 70 mph and have a normal conversation. It's witchcraft.
Volume: 74 dB at idle, 92 dB at WOT, 76 dB at 70 mph cruise
Best for: Anyone who daily drives and values their sanity. Road trip warriors. People with spouses who complain about loud cars. If you're planning to keep this car for years, the extra $120 for zero drone is worth it.
Power Gains: Do They Actually Matter?
Short answer: Not really. All three exhausts performed within 2 whp of each other on the dyno.
- Flowmaster: +6 whp, +5 ft-lb torque
- Borla: +7 whp, +6 ft-lb torque
- Corsa: +6 whp, +5 ft-lb torque
That 1 whp difference? You won't feel it. You won't see it at the track. It's statistically insignificant. Buy the exhaust that sounds best to you — power gains are basically identical.
Build Quality and Fitment
Flowmaster: Aluminized steel construction. Solid welds, good fitment, but the mandrel bends aren't as smooth as premium options. Tips are basic stainless with laser-etched logos. Does the job.
Borla: 304 stainless steel throughout. Excellent welds, perfect fitment (true bolt-on with no adjustments needed). Tips are thick-walled stainless with rolled edges. Lifetime warranty that Borla actually honors.
Corsa: 304 stainless with premium polished tips. The best fitment of the three — every bracket lines up perfectly. Welds are show-quality. You're paying for craftsmanship here.
Rust/corrosion: All three use stainless steel tips and hangers. None will rust through. Flowmaster's aluminized muffler bodies might show surface corrosion after 5-7 years in salt states, but they'll still function fine.
Installation Difficulty
All three are true catback systems (replace everything from cats back) and install the same way:
- Lift car on jack stands
- Cut/unbolt factory exhaust behind cats
- Hang new mufflers and pipes
- Clamp everything tight
- Adjust tip alignment
DIY time: 2-3 hours with basic hand tools (socket set, sawzall or angle grinder, penetrating oil)
Shop install cost: $150-250 at most exhaust shops
Pro tip: All three kits include clamps and hardware, but grab a bottle of anti-seize for the clamp bolts. Your future self (when you inevitably upgrade again) will thank you.
Longevity and Warranty
- Flowmaster: Lifetime warranty (but requires proof of purchase and install by certified shop for full coverage)
- Borla: Million-mile warranty, no questions asked. This is the best warranty in the industry.
- Corsa: Lifetime warranty with easy claim process
The Verdict: Which Should You Buy?
Buy Flowmaster if:
- You want classic muscle car sound
- This is a weekend/track car, not a daily
- Budget is tight and $379 is your max
- Drone doesn't bother you (or you wear earplugs on highway trips)
Buy Borla if:
- You daily drive your S197
- You want aggressive sound without killing your ears
- Build quality and warranty matter to you
- You can stretch the budget to $449
Buy Corsa if:
- You drive 10,000+ highway miles per year
- You're sensitive to drone or have passengers who complain
- You want the absolute best quality and sound refinement
- An extra $120 is worth never dealing with drone again
Our Pick: Borla S-Type
If we had to choose one, it's the Borla S-Type. Best all-around balance of sound, drone control, build quality, and price. The million-mile warranty seals the deal.
That said, all three are excellent exhausts. You can't go wrong with any of them — just pick the sound profile that matches your driving style.
What About X-Pipes, H-Pipes, and Off-Road Options?
That's a whole separate article. Short version: catback exhausts keep your catalytic converters (legal everywhere, passes emissions). If you want more power and sound, look into long-tube headers + off-road X-pipe, but you'll need a tune and might fail emissions in strict states.
Check out our full exhaust category for complete system guides.
— Mason & Son Performance Team