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Discussion Starter #1
Hi all,
I'm new at this site, but I thought this might be the best place to get an answere for my question. So here goes.

I just had a local shop do a custom 3" cat-back system on my truck. They used mandrel bent pipe and a Dynomax muffler installed for $300. I like the new system it sounds great except for a droning sound that hits in top gear on the road when the revs are between 1500 and 1800 RPM's. Then it disappears completely over 2000 RPM's. Is there anything I can do about this? Will the performance chip alter this at all?

Truck info: 2001 Quad/Short 5.9L Offroad, K&N filter (stock intake)

Thanks,
fraceman
 

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Whats a droaning sound? like a vibration or something?
 

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Discussion Starter #3
I guess I'd best describe it as a howl. And it's loud enough to drown out the radio pretty good.

To elaborate further on this; I started out with a Flowmaster mufler (2 chamber) but returned to the shop because of this same droning at 1500 to 1800 RPM's in top gear. The guy at the shop said it was probably just the loudness of the Flowmaster so he swapped it out for me. But the howl is still there even with the new "quieter" dynomax muffler.

So I'm wondering if anyone else has had a similar experience after opening up their exhaust system.

Thanks for your feedback.
 

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im not sure about a droning sound but i like it when my exhaust is too loud to hear my radio...thats why i have flowmaster..lol
 

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Discussion Starter #5
I'm not knocking the exhaust volume level. My previous ride was a 94 ram with a gibson cat-back system that was just right.

my new system is a bit on the quiet side, but has this one sour spot right in the fat part of the power band. Its like a really loud hum (not a burble or rumble), that vanishes after the revs increase further.
 

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Probably a baffle in your exhaust system....happened with my Zr2....goes away as the engine revs up right????


Brett
 

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Discussion Starter #7
Yeah, thats what it does. The funny part to me is that I did the exhaust system to remove all restrictions. How'd it end up with a baffle type sound in the system that wasn't there before? I don't get it.

-fraceman
 

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its probably a resonating frequency that hits just right at those rpm's. the flowmasters are famous for it, i know my charger has that. i think its something you will just have to deal with.
 

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Where does your exhaust exit?,if its a side exit,lengthening the pipes to the rear may help,or change the muffler to a spintech they do not drone
 

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Discussion Starter #10
The exit is behind the axel (stock location). I gues it is one of those things I will learn to live with. After putting some more miles on it, it doesn't seem so bad now.

Thanks for all your feedback.
 

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That soud you are hearing is your cabs harmonics. You might also say the cabs resonate frequence. I used to by big into hi-end stereos (quality not head throbing bass) every cab and inclosure has a certain frequency it amplifies. Hope you can understand this but you might not its kind of hard to explain it you might be better off looking up the terms.
 
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