S650 Dark Horse – Stock Exhaust Pops/Backfire & Noticeably Louder After Break-In?

[turbo707]

TL;DR: Stock Dark Horse exhaust has gotten noticeably louder after break-in and now pops/backfires on decel between ~3,500–1,000 RPM. Also does tracking the car and keeping it high higher RPMs and heat breakdown the exhaust packing quicker.Looking to confirm if this is normal behavior.


S650 Dark Horse – Stock Exhaust Pops/Backfire & Louder After Break-In?

I’m looking for confirmation from other Dark Horse owners on normal stock exhaust behavior.

Car has ~2,000 miles. During the first ~1,000 miles it was driven relatively mildly, then saw a period of frequent hard acceleration / spirited driving and 1/4 mile runs with a track day Since then, I’ve noticed two changes with the completely stock exhaust:

• Audible pops / occasional backfire during decel and light throttle transitions, most noticeable from roughly 3,500 RPM down to ~1,000 RPM
• The exhaust is noticeably louder overall than when the car was new .
• Has any one had any issues with exhaust leaks off any sort or rapid break down of exhaust packing?

No tuning, no exhaust mods, no CELs. This feels like it may be related to break-in, or factory calibration changes (fuel cut, spark timing, or valve strategy), but I wanted to sanity-check with others.


Occurs primarily in Sport and track exhaust modes (less noticeable in Normal).


Questions for the group:

• Is this normal stock behavior as the system breaks in?
• Have other Dark Horse owners noticed the exhaust getting louder with mileage or hard usage ?
• Are the pops/backfires part of the factory calibration, or something worth having checked ?

Appreciate input from other Dark Horse owners—especially those past the 1–2k mile mark or who drive the car hard.

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[npole]

Yes, mine got louder with more miles (stock), but then I got the H-pipe installed and it got more louder.

 

[Alex381]

My GT/CS got noticeably louder past the 1000 mile break in. But that’s because we’re driving them significantly harder after the break In period. That means the engine is running hotter which also makes for louder pops on deceleration. Hell, mine will even backfire in quiet mode.
your experience is totally normal.

 

[Ewags81]

i didn't really notice a difference with break in miles, but I do feel like I get more pops and bangs when the air temp is colder

 

[bountifulgoose]

They use up a lot of fuel, so when you giving it gas and suddenly cut it off to coast or decelerate that extra left over fuel ignites on hot exhaust components. They run on the rich side from factory for a margin of safety so they can be driven on regular to premium fuel and in just about any elevation. With a custom tune im sure they can dial in fueling better and get rid of the pops if someone wanted.

 

[glenng6]

Yes to all, and I don't have a Dark Horse. I think of it as a symphony and consider myself damn lucky to have this exhaust. My heart flutters every time I hear a new sound for the first time! Mine is in track mode 98-99% of the time. Sometimes when I think it is going to happen, I am disappointed when it doesn't. Sit back and enjoy it. It's like fine wine; it gets better with time! Glenn

 

[5LTR550]

Ya mines loud. Sounds cool with ATAK.cant wait to hear it after the whipple and LT’s

 

[schmeky7]

Pop on deceleration is normal. My 2024 GT does it too.

 

[ZXMustang]

You should hear it with my pop flame tune. Lol dont hate, its what the kiddies want.

 

[RKerr]

I am also still full stock on my Dark Horse and have around 2.5K miles on it. I agree with everyone so far that some time around 1K miles the exhaust started to open up more and got more of the pops in the magical 3.5K to 1K RPM range when decelerating and have low to no throttle, as well as being able to force it like bountifulgoose mentioned. These cars just run rich from the factory to help run better at different altitudes and grades of fuel. However, that means it is common for unspent fuel to hit that hot exhaust and Pop!
I do have to add that my Dark Horse is manual and I would be lying if I said I didn't just leave it in gear from time to time when pulling into a parking lot knowing it is going to give off that beautiful low purr/burble and a few pops.

 

[LouG]

I'm not sure if the mufflers/resonators are glass packed on the Mustang. But on bikes with aftermarket exhausts the muffler's glass packing compresses after a while and the exhaust note deepens.
I love the burble on overrun on mine.

 

[N1T3MRE]

TL;DR: Stock Dark Horse exhaust has gotten noticeably louder after break-in and now pops/backfires on decel between ~3,500–1,000 RPM. Also does tracking the car and keeping it high higher RPMs and heat breakdown the exhaust packing quicker.Looking to confirm if this is normal behavior.


S650 Dark Horse – Stock Exhaust Pops/Backfire & Louder After Break-In?

I’m looking for confirmation from other Dark Horse owners on normal stock exhaust behavior.

Car has ~2,000 miles. During the first ~1,000 miles it was driven relatively mildly, then saw a period of frequent hard acceleration / spirited driving and 1/4 mile runs with a track day Since then, I’ve noticed two changes with the completely stock exhaust:

• Audible pops / occasional backfire during decel and light throttle transitions, most noticeable from roughly 3,500 RPM down to ~1,000 RPM
• The exhaust is noticeably louder overall than when the car was new .
• Has any one had any issues with exhaust leaks off any sort or rapid break down of exhaust packing?

No tuning, no exhaust mods, no CELs. This feels like it may be related to break-in, or factory calibration changes (fuel cut, spark timing, or valve strategy), but I wanted to sanity-check with others.


Occurs primarily in Sport and track exhaust modes (less noticeable in Normal).


Questions for the group:

• Is this normal stock behavior as the system breaks in?
• Have other Dark Horse owners noticed the exhaust getting louder with mileage or hard usage ?
• Are the pops/backfires part of the factory calibration, or something worth having checked ?

Appreciate input from other Dark Horse owners—especially those past the 1–2k mile mark or who drive the car hard.

No panic, noted this with my DH after about 1500km (now at 15000km), as for pops and burbles, did increase, but noticed that occurs more after spirited driving and a tank of a certain brand of fuel, fitted a H pipe with Hotdogs and can't drive around town in Track mode anymore, was not aware how loud and defined it really was, till the wife went for a drive, and could hear the crisp crack when she came off throttle at the end of the street.

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