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Discussion Starter #1
There has been a lot of talk about exhaust drone and cabin resonance problems from aftermarket exhaust setups. This seems to make it difficult for people to make a choice on the correct exhaust system to purchase for their cars. At this time it appears no one has found an answer to this problem.

I would propose to anyone who has an exhaust and has to deal with excessive drone that there might be a possible solution. When you tap on a piece of metal, it has a ping to it from its resonant frequency. When we put Dynamat on the metal of our cars for the stereo, this dampens the resonances of the metals and allows more of your music come through. It only makes sense to me that if we put some form of Dynamat under the carpet in the engine areas of our cars, that this would dampen and or change the resonance of the car and possibly reduce the drone. I don't know for sure if it would eliminate the problem, but I will bet that it would help some and lower the overall level of the unwanted sound a few db. If you pull up the back carpet over the back hatch and the engine areas and wrap on the metal, it will surely create a long ping like a musical instrument. After a coating of Dynamat or the like, that ping turns into a short dead sounding thud.

If anyone has done this, please let us know if it helped. If anyone chooses to do it and gets great results, please report to us. I am not that far along with my mods yet, but will be doing this within a few months hopefully.
 

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Hello lovetoturn,
You are correct regarding installing Dynamat sound proofing. I installed Dynamat under the carpet and on the hatch cover over the engine and also on the belt access hatch in front of the engine behind the seats of our 2007 Cayman.
It did reduce some of higher frequencies heard from the engine compartment. It made the passenger compartment slightly quieter.
I was very pleased with the out come and would recommend it to others.
Jim
B C Velocity Exhaust
 

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I have an aftermarket exhaust, non-valved, and I get some drone between 2000 and 3000 RPM. It's worst when he car is going up a slight incline and/or under light acceleration. The strange thing is, it's not 100% consistent. For instance, when I first start the car in the morning and drive to work, it's pretty noticeable. Or, if I'm driving for quite a while (eg, 100+ mi), it gets a little worse (or at least stays about the same). However, and this is the strange thing, if I turn the car off for a couple hours, then get back in the car, for about 5-10 mins, there is almost no drone at all. Around here, a couple hours isn't long enough for the engine/oil to cool down, but I assume the exhaust has cooled down. I just don't understand exactly why the drone is so bad first thing in the morning, when the entire car is completely cold, but nearly non-existent when the car has had a brief cool-down period. At first I thought I was imagining it, but it's every time.

This last weekend I did quite a bit of driving and found that at 3500 rpm at highway speeds (~70 mph), there is absolutely no drone. With PDK, this equates to driving several gears lower than normal. At 2000 rpm, which is about what I'm at in 7th going 70 mph, there is plenty of drone.

I would really like to find a solution for this problem as well, because other than the drone, I absolutely LOVE the sound of the Fabspeed exhaust. I just don't see how Dynamat would fix it since the sound I am hearing is not necessarily all that high-pitched.
 

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Just to add to the confusion a bit, I have found that after a few hours on the highway my auditory system has adjusted to the drone and I simply don't hear it any more. But then I don't hear other sounds either.

Also, my system, Remus, drones much less when cold, more when it heats up. Not at all under very light load, like constant speed on a level road.
 

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I wonder if heat-wrapping your exhausts would give less resonance. Making the metal more taught and forcing more of the vibration/noise out the end of the exhaust rather than leaking through the thin sheet metal of the mufflers.

This would be an inexpensive/interesting project. I have a stock exhaust so I can't do it myself.
 

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Discussion Starter #6
This is a good idea and I have been thinking of using DEI Titanium wrap on the pipes over the axle to mimic the factory ceramic coverings. That will protect the brake hoses and add less heat to an already warm place while on the track. Of course it should make it a little quieter too. There is also a kevlar muffler wrap another member used on his 987 Borla exhaust with success.
 
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