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Technical Topics B48 4-Cylinder Turbo Engine / Drivetrain / Exhaust Modifications g20 320i late 2019 without exhaust flap

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      08-31-2020, 02:43 PM   #1
AlexxZeman
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g20 320i late 2019 without exhaust flap

So I dont quite understand how exhaust without flap works.
Lets say you are lucky and you can close/open a flap, but what do you do if there is no one! If a flap is present it means when its open you get more sounds out of second pipe, but if you dont have a flap, does it mean second pipe is always open? Why there is no more prominent sounds than? Any experience with modding stock exhaust without flap? any ideas appreciated ))
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      09-20-2020, 04:31 AM   #2
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Bump,
still curious,
any ideas, what is different and how it affects sound when driving?
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      09-20-2020, 01:48 PM   #3
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When the flap is closed it bounces the sound waves back into the exhaust. It's like a J pipe modification. The sound waves bounce back into the other waves exiting canceling each other out and making it quiet(think noise canceling).

With the valve open, this does not occur, thus making the exhaust louder. Not by much, but still more bass and tone.

I have the valve and what I did was simply disconnect the connector while it was open and tucked the wiring away. This isn't a monitored CAN signal and does not throw codes.
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      09-21-2020, 08:56 AM   #4
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Quote:
Originally Posted by TheDudeMan View Post
When the flap is closed it bounces the sound waves back into the exhaust. It's like a J pipe modification. The sound waves bounce back into the other waves exiting canceling each other out and making it quiet(think noise canceling).

With the valve open, this does not occur, thus making the exhaust louder. Not by much, but still more bass and tone.

I have the valve and what I did was simply disconnect the connector while it was open and tucked the wiring away. This isn't a monitored CAN signal and does not throw codes.
Thanks,

make 100% sense

Now the question is why some models have a flap and others don't.

So my 320i with M-sport pack doesn't have it, which makes it "loud' all the time. Still, I'm thinking on how to make it even louder ))

Guess first thing would be to remove/replace muffler
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      09-21-2020, 06:13 PM   #5
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Quote:
Originally Posted by AlexxZeman View Post
Thanks,

make 100% sense

Now the question is why some models have a flap and others don't.

So my 320i with M-sport pack doesn't have it, which makes it "loud' all the time. Still, I'm thinking on how to make it even louder ))

Guess first thing would be to remove/replace muffler
I'm not sure why they did that. Almost everything in the BMW lineup has dual exhaust with a flap, except the 320i. If you really wanted to, you can find a 330i muffler and retrofit the flap.

Do you not like how your car sounds?
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      09-27-2020, 02:58 PM   #6
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Quote:
Originally Posted by TheDudeMan View Post
I'm not sure why they did that. Almost everything in the BMW lineup has dual exhaust with a flap, except the 320i. If you really wanted to, you can find a 330i muffler and retrofit the flap.

Do you not like how your car sounds?
Well, for stock exhaust it sound pretty OK.
I think I'll better investigate into aftermarket muffler to improve sound.
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      09-27-2020, 03:19 PM   #7
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Quote:
Originally Posted by AlexxZeman View Post
Well, for stock exhaust it sound pretty OK.
I think I'll better investigate into aftermarket muffler to improve sound.
Yes, good idea. I wish there were more cost-effective alternatives out there for exhausts. In my case, I don't really want a mid-pipe, just the axle-back section.
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      10-02-2020, 05:09 AM   #8
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Looking for smth like this ))
https://shop.bastuck2.de/index.php?c...45010&detail=1
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      10-02-2020, 10:57 AM   #9
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Originally Posted by AlexxZeman View Post
That would be cool. I'm in the same boat. I would totally go for an axle back.
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