Drone

[MaxedOut]

I thought I would re-visit this. I put a 4" exhaust system on my truck two years ago. It's okay empty but hook up my 9,000lb. 5th wheel and I get a noticable drone in the cab - gets louder over 55 - 60mph (short box extended cab). Just curious if anyone has had success in getting rid of the drone. Specific muffler that is good or perhaps you've added a resonator? I've also read on a previous post that Donaldson makes a 4" muffler that is almost as quiet as stock. Any feedback would be appreciated

[Modified]

What brand muffler do you have?
I installed the Banks Monster Exhaust in May 02, and had the drone at 1600-1900 RPM, (about 52-59 MPH). It was annoying, but not terrible. The drone was louder under load.
About one year later, Banks was advertising a new, quieter muffler. I called them to dicuss the drone, and they sent me a new muffler, free of charge. I only had to pay about $20 to return the old muffler.
Now my exhaust has no drone, is comfortable, but sounds good.

[OC_DMAX]

I think anytime you move away from the stock muffler, the end result will be more noise and the possiblility of sound resonances. Most of these aftermarket mufflers are a straight thru design, so you would expect them to be louder. That is the trade-off you are going to make. However, some are certainly better than others.

At an LA Dyno event last year, I had the opportunity to talk to several Banks representatives. They indicated that they had redesigned the muffler on their exhaust system to specifically get rid of the drone that was present. Exactly what MODIFIED mentions above. They added an expansion cavity within the muffler to act as a resonator.

I have a TTS exhaust system on my truck. It uses the Donaldson muffler. This muffler is over 40 inches long. It barely fits within the confines of the trucks underbody structure. There is a very slight drone around 1500 rpm (but it is not annoying, I am just being critical). When stock, my truck also had a very slight drive train resonance around this same 1500 rpm. Other who have used this same exhaust system on Crew Cabs say there is absolutely no drone. Sound is very subjective. Also, resonances are very situational depended. Change a length of exhaust pipe and/or mount it different and the resonances change. It may be that Extended Cab / Short Bed models are more susceptable to these resonances. I am very happy with the TTS exhaust system. I believe it would be next to impossible to adapt the Donaldson muffler to your present 4 inch exhaust (it is too long).

One possible course of action would be too obtain just the Banks muffler and substitute it in place of what you have. This muffler is much shorter than the Donaldson, so a muffler shop should be able to weld it in. I also know that in the Dodge Diesel community, they have been adding Aeroturbine Resonators to their exhaust systems with some success in removing drone.

[MaxedOut]

Modified - It's a Magnaflow cat back system. I don't think they have the same exchange policy as Banks. That sounds pretty sweet. I may look into the Banks quiet muffler though. That's one option.

OC - Yea, I wanted all the benifits of high flow (being juiced) for towing but wanted as close to stock sound as reasonably achievable. I did expect a bit more noise. The muffler shop that sold the system to me said this combination was the one they used on RV's and was not too loud. But it barks pretty good under load and the drone when towing is annoying. I have a friend who manages one of the Gateway Autopro shops. He reccomended trying a resonator. I looked under my truck & I think one would fit. The spot where I'm looking has two flanges but with some fancy welding I'm sure one could be installed. It's intersting the Dodge boys have had luck with the Aeroturbine Resonators. I still wonder if this has been tried with a D-Max. I'd like to try something and I'm leaning more towards the Banks muffler option. At least that sounds like it's a fairly sure thing. Thanks for the feedback