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3 Inch exhaust: how to get it more quiet?

Sjeng

Member
Joined
Sep 3, 2017
I have been using my homemade 3" exhaust for 2 weeks, and yesterday I removed it because the droning was driving me crazy. I now run my 3 inch downpipe into the stock 940T exhaust. This is very quiet but you won't believe how much torque this killed.

The 3 inch system looks like this:

-No cat
-Simons straight through muffler in the middle: https://www.dp-engineering.nl/simons-3-silencer-turbex-stainless.html
-Speedway baffled muffler at the rear: https://www.ebay.com/itm/Speedway-W...ash=item58fc3827d5:g:bp4AAOSwlxRaYO2~&vxp=mtr

I really liked the performance gains and it fits the car like a glove, but the sound (drone) is unacceptable for me.

So my question is: Is there I can do to quieten up this exhaust? Better mufflers?(without killing performance)
And alternatively, are there any good "quiet" high performance systems on the market?
 
I have been using my homemade 3" exhaust for 2 weeks, and yesterday I removed it because the droning was driving me crazy. I now run my 3 inch downpipe into the stock 940T exhaust. This is very quiet but you won't believe how much torque this killed.

The 3 inch system looks like this:

-No cat
-Simons straight through muffler in the middle: https://www.dp-engineering.nl/simons-3-silencer-turbex-stainless.html
-Speedway baffled muffler at the rear: https://www.ebay.com/itm/Speedway-W...ash=item58fc3827d5:g:bp4AAOSwlxRaYO2~&vxp=mtr

I really liked the performance gains and it fits the car like a glove, but the sound (drone) is unacceptable for me.

So my question is: Is there I can do to quieten up this exhaust? Better mufflers?(without killing performance)
And alternatively, are there any good "quiet" high performance systems on the market?
That Simons isn't doing hardly anything and the baffled muffler is probably 90% the cause of your droning. Fit 2 of the biggest Magnaflow oval shaped mufflers you can and it will be very quiet with little to no droning.
 
That Simons isn't doing hardly anything and the baffled muffler is probably 90% the cause of your droning. Fit 2 of the biggest Magnaflow oval shaped mufflers you can and it will be very quiet with little to no droning.

Came here to say this and someone already said it.

+5
 
I'll give a third recommendation for the Magnaflows. I have a 7" and a 5" on my 3" exhaust with no cat. It's very quiet.
 
Bigger muffler. I have the same one but 2.5" with a glasspack and it's not a whole lot quieter than the glasspack alone.
 
I have a single 3 inch magnaflow on my V8 turbo car mounted in the rear, I believe it's 24 inches across? Maybe a little bigger, 100 shipped from summit, my car at idle sounds like a n/a 240 with a full exhaust
 
magnaflows work magic. I have a single 6x6x18 straight though with no resonator or cat and its probably 20% louder than stock. but the piping is only 2.5" which helps in that regard
 
The 3 inch system looks like this:

-No cat

Why? it is stupid to believe you gain 1HP without a cat. The crappy original stuff will reduce the power, buuuuut: A good cat made of metal and with a good geometry at the entry and the out will reduce over 95% of pollution and won't cost any power.....and reduce noise


"You could put in a cat, put in more bends, or put in a bigger/better muffler."

This, two bends at the tail pipe, two times 90? and the car is quiet, ok a lot of less drone.


Regards, Kay
 
Running a longer muffler helps.

+1!

I've also had very good luck with a Morosso spiral flow resonator and Dynomax Super Turbo muffler for an RV. I shoved the largest one I could get my hands on that would still fit in my 240 at the time.
 
i would install 1 or 2 Helmholz resonators T-ed into the 3" pipe , these reduce drone sounds but do not impede flow.
They are basically side chambers that are attached to the main pipe. Some modern cars have them as standard (i believe the stock Camaro V8 exh system uses 2 , 1 on each bank ) just google some pics based on 'helmholz + resonator + car + exhaust' and you will find plenty of examples.

Many normaly aspirated modern cars also have similar (but way smaller) helmholtz resonator chambers attached to the intake system to help quietning down intake noises
 
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I ran a magnaflow and a cat with my 3 inch exhaust ran straight out the passenger side.

No droning *and* enough flow at two feet from the tip to wrap your pants legs skin tight against your shins.

PS, I lived in Birmingham, Alabama at the time and had no need to meet emissions standards. Sure seemed to eliminate lag :e-shrug:
 
I've used Simons straight through mufflers in all of my cars, zero baffled or other types. I would throw those small round ones in the bin and use oval shaped. They have bigger chamber and therefore better ability to reduce noise. With all but 3.5" Simons mufflers you can have the noise on a good level. In those the inner diameter is too big compared to the volume of the chamber.

Easiest and cheapest choice is just to replace the round front with an oval muffler.

If you are going to use straight through mufflers, you can pretty snuggly fit a 420mm(Turbolight) oval to the front and a 500mm(Turbo) long to the back. In a turbo car you might be able to use a 250mm(Turbotight) long front without too much noise. And for a good measure do a original style end pipe from two 90 bends as mentioned earlier. I'd go for 2.5" bends.

And if you want to get rid of stock cat, I'd use Magnaflow 59959.
 
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i would install 1 or 2 Helmholz resonators T-ed into the 3" pipe , these reduce drone sounds but do not impede flow.

Yes! A lot of Z and Infiniti guys are running these. Surprised I didn't think of that earlier. Now just to see if I can find someone that makes a muffler that will fit under my 740.
 
Fit 2 of the biggest Magnaflow oval shaped mufflers you can and it will be very quiet with little to no droning.

MagnaFlow 12219 and MagnaFlow 11249 are what I have on my GLH, they are the biggest that fit my car. Quiet and no drone.
Not cheap, but worth every penny to my ears.


muffler1.jpg

muffler2.jpg
 
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I have an 11" glass pack muffler off of Amazon on my 3" side exit. It drones way less than the ipd/Starla sport exhaust, that I had put a cherry bomb glass pack in the stock location, no resonator. One can even hear the radio while cruising, not so much at wot.
 
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