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Thread: Getting rid of drone -- where to put sound deadening material?

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Posts: 21-30 of 32
2014-03-20 00:48:56
Originally Posted by gomba

It's always been like that. 2 resonators and a magnaflow muffler. Doesn't sound very loud from outside the car or if you see it on the street, but really bassy inside the car at certain RPM ranges.

I have the same drone, I really notice it more than I used to, idk why.
I only have 1 resonator though.
People tell me my car is quiet from the outside....unless im going WOT.
They say riding beside me all they hear is my turbo spooling.

I think I want to mat the trunk floor now also.
2014-03-20 03:46:37
Based on my research when building the branch resonator, I believe the straight through mufflers are what is causing the bass-y drone. You could have resonators instead of every inch of straight pipe in the exhaust system and still have drone. Absorptive mufflers just don't cancel out the 100-200hz tones no matter how big or how many you have. Reactive type mufflers work best in the low range, but they create some high frequency sound that would be buzzy / raspy unless you then canceled it with a resonator.

Source: http://www.enoisecontrol.com/related_articles/engine_exhaust_sound_control_barrier_wall.pdf
2014-03-20 04:09:03
Originally Posted by BenFenner
I hate to say it, but I'm not surprised? Mine drones too...

Make sure that exhaust tip is at least 1/2" past the rear bumper body molding.

Consider a Dynomax VT muffler. I would try one if I were doing this all over again.

Consider a cancer resonator like @MCarp22 designed for the ultimate solution...

Hmmm, I don't even have a tip on the muffler. Maybe getting a tip and extending it a little further out may help? Although I think it's already at least a half inch past the bumper but not sure.

In your defense, the exhaust setup is super quiet from the outside with no raspy tones and sounds really good. I've driven behind the car w/a friend driving my car and the car is quieter than my Maxima w/a stock exhaust (w/a slight leak) lol I can't even hear it spool up. It sounds like a nonturbo car from outside. But it's so damn loud inside. Strange!
Last edited by gomba on 2014-03-20 at 04-15-45.
2014-03-20 04:49:11
Looks like a reactive muffler would help... i wonder who makes that type
2014-03-20 05:21:08
Remus mufflers, I don't think they're made anymore, but that was the best sounding muffler on an SR20 I ever had. My exhaust was only a 2.25" and I had most of the bolt ons but it was awesome.

Too bad can't find them anymore.
2014-03-20 14:07:43
In for answers! My magnaflow resonator + Apexi WS2 combo is a little much for me at my ripe age of 25....

I am considering adding the paint on damping material to my trunk regardless...

2014-03-20 14:32:38
It's also possible to source a BMW muffler and use that? The ones with the vacuum actuated valves that only open under boost. The 335i has two mufflers, one normal one, and the other one has this valve so it acts as a cut-out basically. The car is very quiet until this valve opens... It would be like a Dynomax VT muffler but one you can control with vacuum instead of a spring.
2014-03-20 17:19:10
Originally Posted by unijabnx2000
Looks like a reactive muffler would help... i wonder who makes that type

Reactive muffers are the "turbo" style mufflers and most OEM designs.
2014-03-20 19:55:42
anyone tried using a spiral muffler?

I also found this, its kinda of informative, but they werent designed with 4 cylinders in mind...

Last edited by unijabnx2000 on 2014-03-20 at 20-17-43.
2014-03-21 23:14:31
Flow is flow and I really enjoyed that video and that show! Time to put it to some good use, now!

Thanks, @unijabnx2000
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