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      10-31-2019, 07:04 PM   #1
wrk.eat.drive.rpt
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More sound. Stay CA Smog Legal. HOW?

Hey guys.
Trying to get a little more of that V8 sound out of my e92 m3 but I'm in CA and really not interested in not staying Smog legal.

I have a Dinan exhaust, and scanned the forums, but more require an X pipe that deletes resonator and or deletes cats....

Any ideas would be helpful!
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      10-31-2019, 08:25 PM   #2
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Sell the Dinan... pick up any "race" muffler
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      10-31-2019, 11:42 PM   #3
wrk.eat.drive.rpt
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Ah ok..
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      11-01-2019, 01:25 PM   #4
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Either get a muffler that'll muffle the sound less or take your car to an exhaust shop and have them cut out your secondary cats and resonators. You'll stay smog legal with a secondary cat delete.
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      11-01-2019, 01:29 PM   #5
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Quote:
Originally Posted by sd********* View Post
Either get a muffler that'll muffler the sound less or take your car to an exhaust shop and have them cut out your secondary cats and resonators. You'll stay smog legal with a secondary cat delete.
Smog legal and cat delete in the same sentence.

You will fail visual if they looked under your car. Best option, as someone already mentioned, is get a "race" exhaust or delete the resonators (Not cats).
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      11-01-2019, 01:54 PM   #6
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Quote:
Originally Posted by JsL View Post
Quote:
Originally Posted by sd********* View Post
Either get a muffler that'll muffler the sound less or take your car to an exhaust shop and have them cut out your secondary cats and resonators. You'll stay smog legal with a secondary cat delete.
Smog legal and cat delete in the same sentence.

You will fail visual if they looked under your car. Best option, as someone already mentioned, is get a "race" exhaust or delete the resonators (Not cats).
They don't look under the car for visual, just in engine bay and hooking their system up to check obd readiness. Primary cats are the only ones that'll trigger a CEL and not allow you to pass all the monitors when they check.
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      11-01-2019, 01:55 PM   #7
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Or option 3, move.😎
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      11-01-2019, 02:32 PM   #8
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2011 BMW E92 M3  [0.00]
Buy a good X-Pipe of your choice.

Keep your old X-Pipe.

Swap every time you have to do a SMOG. IT is not that hard to change the x-pipe from time to time.

Or, as others have said, ditch the Dinan cans. I like them, but I am old and I like quieter systems.
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      11-03-2019, 06:58 PM   #9
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Quote:
Originally Posted by ethan9273 View Post
Hey guys.
Trying to get a little more of that V8 sound out of my e92 m3 but I'm in CA and really not interested in not staying Smog legal.

I have a Dinan exhaust, and scanned the forums, but more require an X pipe that deletes resonator and or deletes cats....

Any ideas would be helpful!
Ethan are you in El Segundo by any chance? Removing secondary cats but keep the resonators and a Borla ATAK muffler will sound pretty darn good. Also won't cost an arm and a leg.
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      11-04-2019, 04:03 PM   #10
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I'm in the OC. so relatively close. What if I removed the secondary cats, kept resonators and but left dinan mufflers as is?? Similar?

Also I would assume removing secondary cats would negatively affect smog test no?
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      11-04-2019, 04:07 PM   #11
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Quote:
Originally Posted by Scharbag View Post
Buy a good X-Pipe of your choice.

Keep your old X-Pipe.

Swap every time you have to do a SMOG. IT is not that hard to change the x-pipe from time to time.

Or, as others have said, ditch the Dinan cans. I like them, but I am old and I like quieter systems.
This.
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      11-05-2019, 01:59 PM   #12
wrk.eat.drive.rpt
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Really appreciate the feedback folks!

unfortunately the back and forth changing of x pipe isn't really worth it for me. (just too much hassle) I'm hearing 3 options.
1. Race Muffler- suggestions?
2. Secondary Cat Delete
3. Resonator delete.

Which one will give the most OEM+ feel without being obnoxiously loud?

(OEM+ loud to me means something like what the current oem muscle cars put out in terms of decibels)

What are the key trade offs between option 2 and 3? (Secondary cat vs resonator?)
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      11-05-2019, 02:09 PM   #13
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Quote:
Originally Posted by ethan9273 View Post
Really appreciate the feedback folks!

unfortunately the back and forth changing of x pipe isn't really worth it for me. (just too much hassle) I'm hearing 3 options.
1. Race Muffler- suggestions?
2. Secondary Cat Delete
3. Resonator delete.

Which one will give the most OEM+ feel without being obnoxiously loud?

(OEM+ loud to me means something like what the current oem muscle cars put out in terms of decibels)

What are the key trade offs between option 2 and 3? (Secondary cat vs resonator?)
If you're looking for oem+ I'd just keep the dinan muffler and remove the resonators or secondary cats first. If you remove one and you still want it a bit louder remove both. The dinan muffler does a good job at keeping low rpm sound level quiet while making it louder up top. The downside so a lot of race mufflers is they'll tend to drone which is not really Oem+. You can have a decently loud exhaust without drone which will mean if you want to just cruise around and be quiet you can as long as you'd lower in the rpm range.
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      11-05-2019, 04:57 PM   #14
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Take a look at the Borla Atak. A noticeable bump in sound/volume with no added drone when cruising, go pass 4K and it absolutely screams.

I currently have it paired with test pipes and like it even more.
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      11-06-2019, 12:23 PM   #15
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Awesome feedback....

Considering the secondary cat removal route....
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      11-07-2019, 06:55 PM   #16
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I had a Race exhaust, sounded great but DRONED like crazy right around 2,000 RPM, which is where the DCT tries to keep your revs on the freeway, or any speed really.
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      01-03-2020, 11:34 PM   #17
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Is there a pro and con list between removing resonators vs removing secondary cat?
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      01-04-2020, 01:33 AM   #18
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Removing resonators: raspier, drone, a little louder. No effect on power or smell. As the name implies, they just effect sound waves and deal with resonance.

Removing cats: louder, raspier, smellier, more power. But a good HFC will not hold back much power.

Catless setups on the street are silly, imo. Usually loud and smelly for no real benefit, unless you like obnoxious volume/rasp (quad resonator setups can mitigate this) and the smell of carbon monoxide.

Last edited by wyatth; 01-04-2020 at 01:39 AM..
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      01-04-2020, 02:06 AM   #19
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Quote:
Originally Posted by sd********* View Post
Quote:
Originally Posted by JsL View Post
Quote:
Originally Posted by sd********* View Post
Either get a muffler that'll muffler the sound less or take your car to an exhaust shop and have them cut out your secondary cats and resonators. You'll stay smog legal with a secondary cat delete.
Smog legal and cat delete in the same sentence.

You will fail visual if they looked under your car. Best option, as someone already mentioned, is get a "race" exhaust or delete the resonators (Not cats).
They don't look under the car for visual, just in engine bay and hooking their system up to check obd readiness. Primary cats are the only ones that'll trigger a CEL and not allow you to pass all the monitors when they check.
they looked under my car with a mirror in California for smog.
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      01-04-2020, 05:58 AM   #20
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I know you said you wanted more “V8 sound” but ever consider leaving the exhaust as is and focusing on the induction noise instead? Eventuri plenum gives off an amazing growl and the quality/fit and finish is so top notch no inspector would ever know it’s not oem.
Just saying, the S65 has the ability to make the air going into the car sound just as amazing as the air being expelled.
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      01-10-2020, 11:07 AM   #21
wrk.eat.drive.rpt
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good point!
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      01-13-2020, 11:07 PM   #22
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Quote:
Originally Posted by 850tgul View Post
I know you said you wanted more “V8 sound” but ever consider leaving the exhaust as is and focusing on the induction noise instead? Eventuri plenum gives off an amazing growl and the quality/fit and finish is so top notch no inspector would ever know it’s not oem.
Just saying, the S65 has the ability to make the air going into the car sound just as amazing as the air being expelled.
I was gonna say the same thing, looking to do this mod to mine.
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