Project "quiet car"

My car transmits a lot of road noise and exhaust noise to the cabin. I'm thinking of gutting the interior and trunk and putting down some sound deadening insulation. Has anyone done this yet? I love my exhaust but I would really would like to take the cabin noise down a notch or 2. I drove my moms lexus yesterday and man the lack of all the noises was sweet(the slow acceleration was not)
I also plan to attack the 3-4 interior rattles I have, I'm tired of pushing on pieces to get it to stop.

search `sound tube delete'

I haven't paid attention but I suspect tires are making the most noise, at least at highway speed, with the engine at 2000 RPM.

Why would you want a quiet Mustang? Regardless, the stock exhaust is really quiet to begin with.

Sound tube is coming out next week. The tires could be a partial culprit, 305-35-20 MT street comps, but noise was there when the car was stock, so i'm gonna try to add a new level of refinement.

MultiMediaWill said:

Why would you want a quiet Mustang? Regardless, the stock exhaust is really quiet to begin with.

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I have the corsa sport. Normal driving the exhaust adds very little bad noise. My car will be plenty loud on the outside, I'm just gonna see if $150 or so in soundproofing will make the interior quieter.

I think tirerack rates tires based on noise. But with your tires, swapping those won't be cheap. You can get a dB meter and measure your car and the Lexus at 70 mph to see how they compare.

A layer of dynamat in the trunk wouldn't hurt.

Chameleon said:

A layer of dynamat in the trunk wouldn't hurt.

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I was gonna do some type of sound deadening material from the trunk all the way to the front footwell(if it will fit under the carpet) If I go into the doors I will replace the stock speakers while I'm at it.

This car already has A LOT of sound deadening everywhere. Like others said, sound tube delete helps, and I doubt those are quiet tires.

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What I hear a lot of is tiny stones & crap hitting the wheel well liners, would love to quite that down somehow.

Oh man, subscribed to this thread for sure. I like the engine and exhaust notes of the Mustang, but A) the squeaks and rattles are driving me crazy, and B) I really, really like the idea of refining the interior a bit!

I have done sound deadening. I used dynamat extreme and covered the trunk floor, spare tire well, inside quarter panels and inside fender wells. I considered using a rubber sound barrier, but cheaped out and used the Home Depot cotton insulation. Overall cost was about $160 in materials.

The Home Depot insulation was UltraTouch (Model # 30000-11424 Internet # 100661257 48 in. x 24 ft. Radiant Barrier). One roll will do a trunk easy with probably 1/3 of roll left over. I cut and taped a layer of this in every crevice I could reach, making sure to cut around the ventilation flaps in the rear quarter panels. Lastly, I used the trunk mat as a template and cut a large single piece that fits over the entire truck "floor" under the mat.

I did not take sound measurements, but this made a large change in noise in the cab. I have a Magnaflow Competition exhaust and the drone was over the top at 1800-2000 rpm in 6th gear. The spare tire well acts like a drum head when it is undamped.

I later decided to dynamat the doors to see if I could improve the sound of the stock Shaker Pro speakers. It helps, but nothing magical here.

Good luck with whatever you decide to try.

Thanks for that. I have a large roll of sound deadening material left over from an old project. Never thought about applying it to this car. I find it fairly quiet already - my Focus ST was MUCH louder inside with road noise.

I'm off this week, so might have time to do some db analysis before and after installing the sound deadening material. It will be a good project for me to work on.

The road noise is all tires/road surface (and the fact that it has a much tighter suspension than a Lexus). I-20 where I live has some older rough pavement that is ridiculously loud. The new section that they just paved is Mercedes S class quiet. Pretty amazing difference. I had the same problem in my Civic where switching from Conti pro contacts to Michelin touring dropped it 1dB. Putting insulation in dropped it by another 1dB. Noticeable but not amazing.