I just installed a set of JBA axlebacks on my '06 GT. Although I generally am happy with the tone and loudness, they created a bad resonant drone just off idle up to about 2,000 RPM. Very annoying when taking off from a stoplight. I thought about putting a layer of Dynamat in the trunk beneath the felt pad, however, that stuff is expensive! I ended up with a scrap of leftover plush carpet from our house, cut to fit the trunk floor. Viola! It worked quite well. No more booming drone and the wife's even happy. Give it a try if you have a booming drone from the rear of your car with aftermarket exhaust. It costs very little and you can't even tell it's there under the trunk mat.
I just installed a set of JBA axlebacks on my '06 GT. Although I generally am happy with the tone and loudness, they created a bad resonant drone just off idle up to about 2,000 RPM. Very annoying when taking off from a stoplight. I thought about putting a layer of Dynamat in the trunk beneath the felt pad, however, that stuff is expensive! I ended up with a scrap of leftover plush carpet from our house, cut to fit the trunk floor. Viola! It worked quite well. No more booming drone and the wife's even happy. Give it a try if you have a booming drone from the rear of your car with aftermarket exhaust. It costs very little and you can't even tell it's there under the trunk mat.
Does that really work? Well I'll give it a shot if I can dig uip some carpet from someone.
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2005 Black GT Whipple HO | Oil Seperator | Steeda Tensioner | 93 dyno tune | Autometer Cobalt | GTAs
Before I did the fatmat in the trunk and under the seats, I actually used a moving blanket in the trunk under the carpet. It does make a difference. But a sound dampner does twice the job.
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2005 GT Premium,torch red, all available factory options.
Performance mods: Lets just say it's not stock.
Some people are like Slinkies. They're really good for nothing. But they still bring a smile to your face when you push them down a flight of stairs.
With JBA axlebacks, there is really no drone once you get underway. Drone is the result of an engine under load when you accelerate at low RPM's. You get it when taking off from a stoplight from idle to 2,000 rpm and on the highway in 5th gear between 50-60 mph under a load. Again, low engine speed when accelerating. If you don't lug the engine, there is no steady state drone, just sweet music from the engine. The carpet went under the existing trunk mat and you can't see it. It made the booming go away. I considered Dynamat but it's $150 a roll. By the way, Ford delivered these cars with a "nude" trunk. No padding, no sound deadening at all. My old 5.0 LX had at least 2-3 layers of heavy padding underneath the hatchback trunk mat. Maybe the noise is part of the deal.
I just installed a set of JBA axlebacks on my '06 GT. Although I generally am happy with the tone and loudness, they created a bad resonant drone just off idle up to about 2,000 RPM. Very annoying when taking off from a stoplight. I thought about putting a layer of Dynamat in the trunk beneath the felt pad, however, that stuff is expensive! I ended up with a scrap of leftover plush carpet from our house, cut to fit the trunk floor. Viola! It worked quite well. No more booming drone and the wife's even happy. Give it a try if you have a booming drone from the rear of your car with aftermarket exhaust. It costs very little and you can't even tell it's there under the trunk mat.
Great idea Tungsten. Been debating on the all the sound reducing products that have been recommended from this site, but their so costly, even the QuietCar product after determining I'd need about 3 gal's to do what is recommended. Think I'll give your idea a test and see. Piece of plush remnant just might do the trick.
I remember when Dynamat first came out in the 70's. One of the points that was made is that you do not need to cover the entire panel. Just covering a relatively small area will deaden vibration.
I remember when Dynamat first came out in the 70's. One of the points that was made is that you do not need to cover the entire panel. Just covering a relatively small area will deaden vibration.
Ahh, then that might make the dedicated products affordable. I was assuming the entire area needed covering. My primary attention is in the trunk area where there is nothing but the thin carpet mat over the trunk well and cardboard on the side panels, great source of noise and resonance. Thanks 65sohc
I have been trying to kill the noise from my gears. I dynamatted teh entire under backseat area..... didnt really do the trick and cost me a lot..... then i found out what dynamat is made of.... Polymeric Mastc..... i went on McMaster-Carr's website and bought a roll for 1/3 of the price and did the entire trunk.
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2005 Mustang GT , 5-speed , Satin Silver
Mods: C&L, custom SCT tune, Stage 3 Comp Cams, Flowmasters, OR h-pipe, Steeda UDP, 4.10 FRPP gears, Zex Wet Nitrous Racer Kit, SPEC 3+ w/ alum Flywheel, Detroit True-Trac, full BMR suspension, PH alum driveshaft, M&H, SS window louvers, GTS center panel blackout
12.88 @ 106
12.03 @ 115 (75 hp shot)
Was out shopping today for some carpet remnants and a light bulb went on as I saw some carpet padding Why not try that vs. the carpet. Went to a local carpet wholesaler, asked for some 1/2"-8lb padding. they happened to have some left over from a previous job and just gave me the padding, no charge (about a 10x10 piece). Cut it, using the trunk pad as a template and also filled in where the spare goes. Took car out for a local spin, windows up, A/C on and wouldn't you know, the exhaust noise and drone resonance has definately been reduced. Still have plenty left over to do under the rear seats if I get the hankering.
I was actually at home depot today looking for a special kind of carpet padding. I htought the foam would work ok but there is a grey felt capet padding which is usually used for basements (moisture reasons). This is about the same thickness as the foam but is denser and i think will work really well to deaden any noise. Ill report back when i put it in.
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2005 Mustang GT , 5-speed , Satin Silver
Mods: C&L, custom SCT tune, Stage 3 Comp Cams, Flowmasters, OR h-pipe, Steeda UDP, 4.10 FRPP gears, Zex Wet Nitrous Racer Kit, SPEC 3+ w/ alum Flywheel, Detroit True-Trac, full BMR suspension, PH alum driveshaft, M&H, SS window louvers, GTS center panel blackout
12.88 @ 106
12.03 @ 115 (75 hp shot)
Ahh, then that might make the dedicated products affordable. I was assuming the entire area needed covering. My primary attention is in the trunk area where there is nothing but the thin carpet mat over the trunk well and cardboard on the side panels, great source of noise and resonance. Thanks 65sohc
I remember the Dynamat display at a local stereo shop. They had two sheet metal panels, similar to doorskins. One had a piece of Dynamat maybe 4x4 inches. When you whacked the naked sheet metal with a small hammer it made the typical ringing sound. When you hit the Dynamatted panel it just made a dull thud with no reverberation. As I think about it, a carpet lies on top of the panel and absorbs some of the sound energy passing through the metal. A product like Dynamat is permanently affixed to the panel so that it must change the vibration characteristics such that the panel itself generates less sound. Most of the objectionable exhaust noise is not coming out the tailpipe but is the result of harmonics of the various pieces of hardware. Ford designed the exhaust system to allow maximum actual exhaust sound with minimal obnoxious harmonics which I think is why there is no insulation in the trunk area. It isn't needed. My Mustang overall is much quieter than the last two cars I had-a 94 Supra Turbo and a 2003 Z4. I'm no expert on this stuff. I've never even used Dynamat (though I have a big roll ready to plaster all over my '65), but I think that is the concept.
Fixed Drone with Carpet 
Drone dried up 
Why not try that vs. the carpet. Went to a local carpet wholesaler, asked for some 1/2"-8lb padding. they happened to have some left over from a previous job and just gave me the padding, no charge (about a 10x10 piece). Cut it, using the trunk pad as a template and also filled in where the spare goes. Took car out for a local spin, windows up, A/C on and wouldn't you know, the exhaust noise and drone resonance has definately been reduced. Still have plenty left over to do under the rear seats if I get the hankering. 
