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I was just curious about something. I have rear bumper off right now and I was driving the car yesterday and the exhaust was MUCH more quiet. In fact you couldn't even really hear it above the radio. When the bumper is on, the exhaust is much louder and the drone can get loud around 2800 rpm. I have a CWest rear bumper (fiberglass) and I was wondering if anyone had tried to dynomat their rear bumper to see if that made the exhaust sound a bit more quiet?
 

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Wxman, the sound is less with the bumper off because the sound is escaping from beneath the car mush easier with the bumper off. Maybe you have the exhaust tip a little to much inside of the car, making the drone much more noticeable. Extend the muffler tip so its farther away from the rear bumber so it helps the sound exit more easily. Ive had those problems before.
 

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Wxman said:
I was just curious about something. I have rear bumper off right now and I was driving the car yesterday and the exhaust was MUCH more quiet. In fact you couldn't even really hear it above the radio. When the bumper is on, the exhaust is much louder and the drone can get loud around 2800 rpm. I have a CWest rear bumper (fiberglass) and I was wondering if anyone had tried to dynomat their rear bumper to see if that made the exhaust sound a bit more quiet?
the reason for that is the way sound travel. with a bumper on, the sound waves from the exhaust will bounce back and forth (vibrate) from the bumper. this will cause the drone and the sound to increase in volume. without your bumper, the sound waves can escape easily and thus, you can barely hear it...
 

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Marc, I think if you dynomat the bumper, you'd have more of a droning than before.

If you wanted to get rid of the sound, I'd actually cut holes in it.
 

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OR maybe you could put some sort of downward sound deflector at an angle relative to verticle and horizontal towards the front of the car... that would deflect the sound waves down and away from the car instead of back in towards it (the inner shape of the bumper is almost a parabolic reflector directing sound back in towards the car from certain angle.
 

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dasgalloway said:
OR maybe you could put some sort of downward sound deflector at an angle relative to verticle and horizontal towards the front of the car... that would deflect the sound waves down and away from the car instead of back in towards it (the inner shape of the bumper is almost a parabolic reflector directing sound back in towards the car from certain angle.
:eek: i didnt understand much but you get 3 dots for that my good man :D
 

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i think the sound was trap and was vibrated which produces a drone, sounds travel through vibration waves from what i understand of them.
 
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