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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > NA Engine (non-turbo) / Drivetrain / Exhaust Modifications > 325i PE Exhaust - May need help to reduce dB



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      11-28-2012, 05:34 AM   #1
dragon20
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325i PE Exhaust - May need help to reduce dB

Hi all,

I have a E90 325i Euro version.

I bought a PE exhaust from Titsher and got it installed a while ago. Its great!!!

After a few months I noticed it got a little loader.

I must admit that I now drive my car and think it can be a bit loud on some days.

I am in Australia and the noise regulations for exhausts is maximum 90dB. I wanted to ask if any one knows what the PE is rated at?

Once I get it tested I may have to reduce the noise under 90dB if its over. At the moment I have the full PE setup (muffler + straght throuh pipe). There is no resonator as per the stock exhaust.

Iam thinking of taking it to a good exhaust shop and fitting a resonator to reduce some of the dB. I wanted to ask if any one can reconmend a resonator that is a good fit and reduces the noise a little (dont want to reduce it too much!)

Any help would be ace

Cheers!
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      11-28-2012, 07:19 AM   #2
Wrngway
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BMW doesn't give out too many specifics on the exhaust. I've heard there are a couple different versions. In Europe I think it just includes the rear muffler section. The version in the U.S. has two sections...the muffler, and a midpipe which deletes the resonator.

As far as the volume goes, you may just have an exhaust leak. I'd check out that possibility first as it's the easiest to fix. From what I've heard of the PE, it's a relatively quiet system compared to some options out there like a muffler delete.
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      11-29-2012, 05:46 AM   #3
dragon20
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Hi thanks for the reply. Yea I definitly have the US version which comes with a midpipe / resonator delete. I spoke to exhaust shop today and they said you will definitly know if you have an exhaust leak. I am going to get the noise tested and also get them to check.

Does any one have any reconmendation on a resonator that will fit in the stock location (near the rear muffler) and quiet the exhaust down a little? anything would be great

Cheers
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      11-29-2012, 08:03 AM   #4
mthomas
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Smile

I hear the stock exhaust is rated under 90db.
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      11-29-2012, 10:12 AM   #5
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Unfortunately I just tossed my OEM resonator, although the cost of shipping it to you might've been more than the part itself.

I also just remembered that the PE muffler has a provision to attach a drone reducer. It's a conical shaped rubber piece that may have been attached to your stock muffler. You just bolt it on. They're designed to reduce noises in a specific frequency range. My car didn't come with one, but you may still have yours.

If you happen to get it the noise level measured, let us know the result.
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      11-30-2012, 06:38 AM   #6
dragon20
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Do you know what this drone reducer looks like or where exactly it attaches to?

I am doing the test on Tuesday so I will let you guys know

I would prefer to not put the stock resonator and get somthing a bit smaller / lighter.

If any one has advice on aftermarket resonators e.g. magnaflow it would be great to post your experience.

Cheers
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      11-30-2012, 07:43 AM   #7
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Quote:
Originally Posted by dragon20 View Post
Do you know what this drone reducer looks like or where exactly it attaches to?



You should be able to find it in the parts diagrams at http://realoem.com/bmw/showparts.do?...89&hg=18&fg=20. It wasn't attached to my car and may have been eliminated for the LCI models, but my original muffler still had provisions to install it. The PE muffler also has the attachment point. All you need is the rubber piece and the bolt to attach it.

I can't say if it would help or not, but it's a low cost option.

Here's some info from realoem.com on a Euro 325i, early 2006 build.



20 Vibration absorber 32 HZ 1 18303413587 $54.00
21 Collar screw M8X70 1 18407540023 $4.07

Last edited by Wrngway; 11-30-2012 at 07:51 AM..
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      11-30-2012, 12:56 PM   #8
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Here's a thread that talks about other available vibration absorbers.

http://www.1addicts.com/forums/showthread.php?t=566845
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      12-03-2012, 06:14 PM   #9
dragon20
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Guys, I fitted the stock drone reducer today.

and got the test at the exhaust shop.

They tested the car at 4425rpm

the Db was as follows
92db acceleration
98db De-cceleratrtion

This has now caused me an issue where I need to reduce this by about 5 to 6db.

Considering its de-celleration does any one have any reconmendations on what kind of resonator I should go for? any advice would be great!
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      12-04-2012, 04:23 PM   #10
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2008 BMW 328xi  [8.20]
Wow, I have a BMW PE with secondary cat delete and I still don't think it's loud enough! To each his own, I guess. Or make sure your clamps didn't come loose anywhere.
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      12-09-2012, 10:06 AM   #11
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Before doing any changes. You may want to find out how the cops do measure if it is too loud or not. As it depends at what area they test it from. Is it right at the exit at muffler? At ear level standing next to it? Where they measure it from can have a big impact on reading. As they are different standards on measuring noise. db(a) is a standard that is common in North America which in short is measured at certain distance at varying degrees on a compass and averaged out.
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