The Magnaflow muffler I have seems to have "broken in" meaning I guess the packing material has started to lose it's effectiveness.

At about 60-70mph I'm hitting the "drone zone" at about 2000-2200rpms. I love the sound of the Magnaflow muffler around town but the drone is killer if you've got to be in the truck for any length of time.

I've looked into Resonator tips, but they look like they are all basically small glasspacks and I'll just end up replacing them again in the future. Are inline exhaust resonators basically the same thing? Anybody seen any other designs out there? I saw an Edelbrock muffler that had a Helmholtz Resonator in it, but I really don't know what that one would sound like.

Anybody got some ideas on a new muffler, resonator, or resonator tip that isn't a glasspack (or the stock water heater sized muffler)?

 

what is your tail pipe length from the end of the muffler to the open tip?

avoid lengths in the 55 to 75 inch range
or you will have
a kind of 'flute' or 'church organ pipe'
that amplifies the drone

a resonator anywhere from the middle to the end of the tailpipe
will probably cut the drone in half or more

I put a 16 inch long DynoMax Ultraflo stainless steel round muffler
on as an exhaust tip to kill drone in the 1500 to 2000 rpm range

 

Well Hank,

Just measured it and it's 68". So that's right about dead smack in the middle of what you posted. I measured up to the first hanger where the exhaust starts to curve up and over the back axle and that's right at 48" inches, so maybe I can have my exhaust guy flip the muffler and patch tubing he added to replace the length of the old stock muffler and get it under 55". If you're claim is true about the exhaust resonating like a pipe organ tube, then a shorter tube will only resonate at a higher frequency and that should be in a RPM band much higher than highway cruising speed.

Would that be your assessment as well? Is there any rule about how close the muffler should be to the cat?

 

Yes, a shorter length will move the drone to a higher rpm
and there have been posts where Ram owners who have gone to
side turn-outs have reported improvement

For a quick temporary experiment
you could slip on a length of exhaust to your tip
and see how low an rpm the drone moves to

I don't know how the rear outlet of your muffler is fixed
but if it is a clamp
you could consider a temporary experiment with a side turn out.

Warning: geek talk follows.....
the rpm at which the drone occurs is also dependent on
the "speed of sound"
in the hot exhaust gas
so an engine running at a wider open throttle will also
have the rpm of drone shift a bit...
you sometimes hear this on hill climbs

I think you can move the muffler closer to the catalytic converter
in your adjustment
but there is no getting around that hotter objects corrode a bit faster
but with stainless it should not be a problem

 

Thanks for the help Hank!