Hey guys...

I've got a '07 4.7 quad cab, short bed. I've replaced the stock muffler with a 18" ( I think, it might be 14") universal Magnaflow. It sounds AWESOME. Unfortunately, It's got too much drone on the freeway.

Any ideas about how to deaden it? Has anyone tried to Dynamat the underside of the bed?

If I were to change to a brand name catback, would it change my drone?

Or maybe there's a specific exhaust that sounds good, but doesn't drone?

 

Don't see how'd you get the drone with that engine... i would'nt have changed mufflers.. i'd probably just run straight pipes.... Should sound fine... loud... but fine....Now if you told me you had the 2007 5.7... I'd belive you....

 

In most factory style mufflers there is a funny looking section inside
called a 'Helmholz Resonator'
that gets rid of the drone.

http://www.howstuffworks.com/muffler3.htm



If you put on a muffler without a Helmholz Resonator
you need to avoid certain tailpipe lengths in the 55 to 75 inch length.
Go shorter (side exit perhaps)
or go longer
or put a resonator in the middle.

The tailpipe length is like a musical instrument
similar to an old fashioned Pipe Organ in a church
or a flute.

 

I've got a flowmaster 40 on mine and I don't have a drone. My 93 Cobra with flowmasters definatly has one, but not the truck. One question that I have is are you running a tailpipe or a dump? If it's a dump, get it out from under the bed. It's a ton louder with a dump under the vehicle.

 

I have the sam problem Matt. I just installed a magnaflow system (with 18in muffler) on my 05 hemi and the cabin drone is loud. I know everybody has a different view on loud but i'm wondering if it could have something to do with the system not being clamped down tight enough. I am trying to decide if I should send it to the shop to get checked out (everything tightened down better than I did it) orshould Isend it in to get the 24in muffler. Everything i've learned on this forum about different exhausts tell me that this shouldn't be this loud inside the cabin.

 

Listen to an hour of heavy metal as loud as you can and you won't hear the drone...

 

I only listen to heavy metal. =) loud. With subwoofers.

And I still have lots of drone. =(

I'm going to measure my system, to see if I comply with HankL's remarkably knowledgeable response.

I can't (or rather more like won't) go shorter, since my muffler itself sits just right forward of the axle, so a pre-wheel dump won't happen. But maybe I can go longer, get a Y and spread to a straight out the back dual?

Hmm..

 

Ha Ha I end up taking my 20 inch Maganflow off going back to a stock type muffler it no Helmholz in it this Muffler is it nice sound NOT LOUD AT HWY Speeds just right.

 

big reason i changed from magnadrone to flows...the dreaded drone...

 

big reason i changed from magnadrone to flows...the dreaded drone...