Exhaust crackle and pop?
 

Hi everybody

I've been looking at a few exhaust for the FRS and there's just something I find a bit boring about it. The sound it makes when throttle is open is nice, but on the overrun it sounds quite lacking, it's just a smooth note back down to idle. Is there anyway to add in some nice crackle and pop back in like these cars?

[ame="http://www.youtube.com/watch?v=u2gUsy1Yn4U"]Megane 3 RS 250 Cup 3" K-Tec Exhaust and 3" Decat part2 - YouTube[/ame]

[ame="http://www.youtube.com/watch?v=f1jUsligR-I"]2011 MINI Cooper S Exhaust "Pop and burble" - YouTube[/ame]

I'm not an engineer or expert on engine and exhaust tuning, but from what I can find on the internet the cause is that the throttle is still open very little on the overrun, the unburnt fuel enter exhausts and that is whats causing the crackling. The thing is that the frs (like most cars) cut the throttle fully on the engine deceleration, but when the rpm gets close to idle the throttle needs to be opened again to prevent it from stalling. So if you listen closely in the video below around the 0:18 you can hear a few slight pops when its nearing idle as the throttle is opened automatically by the ecu.

The Mini Cooper S shown above only creates that sound when in sport mode, so I believe it is mostly the engine tuning that controls it. Which got me wondering if it is possible to get something similar on the FRS with an ECU tune.

[ame="http://www.youtube.com/watch?v=cXYnyvJEDDA"]GReddy Racing SP Elite -Exhaust - Scion FR-S - YouTube[/ame]

The pop and burble are more obvious in this video below, even has some visual cues (notice the exhaust gas coming out)
[ame="http://www.youtube.com/watch?v=kwxqyn4IBj8"]Scion FRS and Subaru BRZ FT-86 SpeedFactory V1 Exhaust - YouTube[/ame]

A turbo or modified car will normally produce more of this overrun popping sound, mostly because of the extra fuel. But you seem to have it nailed, it's in the tune. Having the car run a little rich on decel will cause some nice pops and even spits of fire on a car with a straight through exhaust. Running catless helps too, since a lot of the unburnt fuel burns up in the cats. (this is likely why the car in the video you posted is doing it it)

I'm a big fan of this sound as well, my Vette makes awesome noises on decel. Brake HARD into a turn, heal/toe down 2 gears, blipping to 5k+, listen to the spits of hellfire popping out the back of the car... my personal favorite part of driving a modified car. Listen to some F40/F40LM clips on YouTube if you want to hear CRAZY overrun popping!

A front pipe with a high flow cat adds some crackle and pop. Paired with a nice axleback or catback and it sounds nice.

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I hear some nice burbling and pops on deceleration 90% of the time with my Invidia catless frontpipe and Invidia N1 catback. I'm getting Unichip soon, so it will be interesting to see how this effects the sound. My guess is that Unichip will lean it out a little more... I think that means it will also be decreasing the magnitude and frequency of the backfires?

You should hear my Guzzi on a hot day on deccel. Not so sure its a good thing though.

My Triumph Street Triple R with a Competition Werkes Shorty gets some pretty nice pops on decel and revving :D

My SRT fullheaderback does this. I'm running a bit rich up top so when I rev her out I get some in my soundtrack

I have Motiv Concepts over pipe, track front pipe, stock mid pipe, and Mach V dual muffler delete and I get all kinds of crack, burble and pop. LOUD, but damn I love the sound.

For some reason I thought of Rice Krispies when opening this thread.

I made my own axle back and i get this noise when i downshift while im driving hard.

[ame]http://youtu.be/g_UeniEhdQc?t=9m56s[/ame]

my car pops and burbles stock... lol

i think that yellow car in the op has antilag.

U aint bout life cuh