Well I got a Donaldson 34" muffler and put it on about a week after I got my truck in June. I had no drone and I loved the thing to death. I now have about 12000 miles on it and the drone at 2100--2200 RPMSs is killer. Sadly it is almost impossible to avoid that RPM range because it really likes to stay trhere when you are pulling something. I find myself letting off or flooring it to get it past that crappy area because it hurts my ears and everything in the truck is vibrating. And it seesms like it just keeps getting worse. I never did have exhaust hangers added, and has resonated exhaust tip. I strapped some 2" angle iron to the pipe to no avail. I am thinking of trying some real heavy rasp bar out of a Deere combine we have out in the shed and seeing if that helps because it will be a lot more mass than the AI. I want to fix this without chasing a bunch of wild geese...

What should I do?

 

bin there tried that lol, had a mbrp, and a magnaflo, drone was insane pulling, had to go back to factory muffler no cat, this muffler flows very well, do a dyno pull with the noisey one then do one with the tock muffler, very close, and the same for the egts, that was my experience, did not want to go back to stock either but had to or will be wearing a hearing air by 40 lol.

 

I added an extension w/ turn down to my pipe and eliminated in cab drone and a smoked-up fender. I think getting the tip past the body has helped more than the turn down.

 

A quick/easy option for you may be to put a small resonator in-line before the muffler, just after the downpipe. I have the same muffler as you. I'm over 10K and I have no drone issues to speak of. However, my issue is that it has gotten progressively louder as I have bombed the truck. Opening up the exhaust side with the ATS manifold, bigger turbo w/ bigger turbine opening, Banks DP, etc., has all contributed to the exhaust being much louder than when it initially went on (it was sweet back then).

http://shop.airflowonline.com/Mercha...ategory_Code=R I have one of these awaiting the new turbo to arrive. Plan on putting it on at the same time. These run $40 to $50 if you pick it up locally at a muffler shop or semi repair facility. That web site is expensive. Just cut out a section of pipe with the sawzall, and clamp it in with 2 4" exhaust clamps. 4" exhaust pipe slides inside each end of this thing. Easy stuff. Just think'n out loud.

 

So you think a resonator is the way to go then?

I had that as one of my ideas and

Also maybe going to the 51" Donaldson

Rasp bar instead of angle iron

Hangers on the new muffler to help eliminate some vibe.

Any combination of these things

WHat exactly would the resonator achieve do you think?

 

We have had good results reducing or eliminating drone using an Aeroturbine as far forward in the system as possible. It can also help to remove the cast elbow and smooth it out inside with a flapper wheel.

 

sound deadener in the cab!!!! makes a HUGE difference...

my truck is quieter inside w/ 5" straight pipe after I added a bunch of sound deadener than it was before with a big muffler on it!!

Forrest

 

Don't know if it would be the best way to go, but definitely the cheapest route that is guaranteed to make a difference. Clamp that sucker on under the shade tree over a few cold ones. Just don't know if it would be a good difference, or bad. Hard to say. Resonators are a quieting device. No doubt it will do what I want, but your flipping a coin with drone. If I remember correctly, drone is a result of the frequency generated by vibration in the exhaust system. Not vibration caused by loose clamps or hangars or anything per say, although, you do want enough hangars to properly support the system. Just pushing exhaust through a pipe will create vibration. Any changes made to the flow of exhaust will change the vibration, in turn changing the frequency. Question is, whether it will change it in a way that totally gets rid of it, or just move it to a different RPM range. The fact that it will change it is the only guarantee you have. I suspect it will help. Many folks have put the Aeroturbine in line to combat drone, and it works. The Aeroturbine is doing nothing more than changing the flow, which changes the frequency. Resonators should have the same effect, and about $100.00 cheaper. There are a few folks here with the 51" muffler and report no drone, so that would be a viable option too. Just takes more work.

The trick with clamping angle iron to the pipe is to add weight on long, straight stretches of pipe to effect the vibration, hopefully effecting it for the better. If the angle iron didn't help, I suspect rasp bar won't either. You don't want but so much weight hang'n under there. If it is free though, I'd try it.

If you decide to try a resonator, make sure you report back. Lots of folks here with drone problems that could benefit if it takes care of it.

I should have mine on this coming weekend, or mid week next week, depending on when the new turbo gets here. No drone issues to report on, but I can let you know exactly how it effects what I've got going on.

That was long. I talk too much.

 

The idea of using a resonator or Aeroturbine far forward in the system is to change the frequency of the exhaust and there by move the drone out of your normal operating rpms. Hopefully it can be tuned out completely by doing this.

 

Forest Nearing, talk to me about the sound deadening! spinlocker@yahoo.com