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M2 Technical Topics > N55 Engine / Drivetrain / Exhaust / Bolt-ons / Tuning > exhaust notes doesn't sound right anymore

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      01-04-2021, 02:42 PM   #23
D CHOI
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Installed the catless downpipe today and it fixed the sound issue that I had. Now the car feels right and even better from 200 cell catted to catless. The burbles are more litt and I feel the turbo breathing better. Also the start up exhaust roar (bm3 tune) sounds louder and meaner.

Here are the pics of the fabspeed 200 cell HJS catted downpipe. It doesn't look too bad but maybe the inside got damaged or clogged somewhat.
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Last edited by D CHOI; 01-04-2021 at 03:06 PM..
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      01-04-2021, 05:35 PM   #24
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Doesn't look as bad as mine but the outside part doesn't look right to me.
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      01-04-2021, 06:33 PM   #25
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Quote:
Originally Posted by D CHOI View Post
Installed the catless downpipe today and it fixed the sound issue that I had. Now the car feels right and even better from 200 cell catted to catless. The burbles are more litt and I feel the turbo breathing better. Also the start up exhaust roar (bm3 tune) sounds louder and meaner.

Here are the pics of the fabspeed 200 cell HJS catted downpipe. It doesn't look too bad but maybe the inside got damaged or clogged somewhat.
yea that's definitely damaged. Good thing you caught it pretty early
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      01-04-2021, 06:34 PM   #26
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Quote:
Originally Posted by Oktom2 View Post
Doesn't look as bad as mine but the outside part doesn't look right to me.
Yea I'm not sure what caused it maybe the race fuel or e85. I noticed some of my fi exhaust had some minor black markings too.
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      01-17-2021, 02:02 AM   #27
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Originally Posted by Oktom2 View Post
Doesn't look as bad as mine but the outside part doesn't look right to me.
Yea I'm not sure what caused it maybe the race fuel or e85. I noticed some of my fi exhaust had some minor black markings too.
Too bad it's not stock, the warranty on the original cat in the US is 8 years or 80,000 miles.. But I guess you have to pay to play..


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      01-18-2021, 05:30 PM   #28
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To much fuel to make more aggressive pops will damage any cats. On the old N54 cars there was a way to make those cars pop and bang real loud and it destroyed the cats real quick. Here is a picture of my fabspeed cat after 8800 miles with a mild tune and stock bmw pops. Just like new.
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      01-20-2021, 05:30 AM   #29
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To much fuel to make more aggressive pops will damage any cats. On the old N54 cars there was a way to make those cars pop and bang real loud and it destroyed the cats real quick. Here is a picture of my fabspeed cat after 8800 miles with a mild tune and stock bmw pops. Just like new.
100% agree - agg burbles/excessive overrun popcorn and catted DP's don't mix....
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      01-20-2021, 03:41 PM   #30
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Originally Posted by Poochie View Post
Too bad it's not stock, the warranty on the original cat in the US is 8 years or 80,000 miles.. But I guess you have to pay to play..


.
I will tell you from experience in the legal field, that federal emissions warranty is barely worth more than the paper it is printed on. The hoops you have to jump through for enforcement are absurd, and even going to court you face an extremely uphill battle thanks to some bad precedent (at least in CA, I can't comment from experience outside of that jurisdiction).
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      01-21-2021, 01:04 PM   #31
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Originally Posted by Poochie View Post
Too bad it's not stock, the warranty on the original cat in the US is 8 years or 80,000 miles.. But I guess you have to pay to play..


.
I will tell you from experience in the legal field, that federal emissions warranty is barely worth more than the paper it is printed on.
I was speaking specifically on extension of the warranty related to the catalytic converter, for 8/80k miles, if still have the stock unit installed.

I'm positive it exist and is mandatory, as when this summer, the dealer handed me a print out of my remaining coverage and it listed this specific coverage that was itemized separately.

This endorsement also listed in the back of your vehicle's manual. It's a federally-mandated law, not an optional service that they can pick and choose to enforce.

https://www.consumerreports.org/cro/...-bmw/index.htm

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      01-22-2021, 06:12 PM   #32
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Originally Posted by Poochie View Post
I was speaking specifically on extension of the warranty related to the catalytic converter, for 8/80k miles, if still have the stock unit installed.

I'm positive it exist and is mandatory, as when this summer, the dealer handed me a print out of my remaining coverage and it listed this specific coverage that was itemized separately.

This endorsement also listed in the back of your vehicle's manual. It's a federally-mandated law, not an optional service that they can pick and choose to enforce.

https://www.consumerreports.org/cro/...-bmw/index.htm

.
I understand what you are saying, and yes it exists, but enforcement of the warranty is another matter. I am speaking from years of experience in this field.
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      02-02-2021, 08:07 PM   #33
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Another update on my sound issue. It turns out my resonator on my fi exhaust had some leaks/cracks. Now the back pressure is back and the pops are more solid and aggressive. Exhaust note sounds more tight too.

Not sure how the resonator got damaged but I'm thinking it's the probably the aggressive burbles and the popping.
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      02-03-2021, 01:08 PM   #34
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My stage 0 MHD flash has less aggressive burbles than BMW stock.

300cel downpipe. I don't mind too much as car aou da great when on it and the burbles were very loud before.
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