I'm tired of the drone from my Magnaflow system. I'm looking to change out a much quieter muffler. I'm thinking the Walker SoundFX or Dynomax Super Turbo. Are any of you running them, or have experience with them?

I'm open to other suggestions too.

 

Install a larger magnaflow muffler. Which one do you have on there now?

 

Do you have full tailpipe(s) exiting from under the vehicle behind the rear wheels? If not, any muffler is going to drone in the cab.

 

Exhaust drone & exhaust noise while both are different by definition, both are created as a result of impactors/promoters. Exhaust drone is that which is caused by harmonics- a sound wave generated which in essence takes the exhaust sound and sends it back up the exhaust system (towards the engine) and is released or transferred into the passenger compartment. This transfer typically happens where large contact areas exist that have little to no sound dampening qualities and/or materials- as a result of the muffler construction or vehicle manufacturer.

Exhaust Noise (in passenger compartment) is what most people actually complain about. While harmonics do play a contributive role, it is not the primary cause.

Impactors/Promoters

I would love to tell everyone that “x” is the cause 99% of the time for exhaust noise complaints, but it is typically a series or combination of numerous factors which leads or develops the level of noise which is uncomfortable to the ear. The first “rule” of an exhaust system is that the noise should be generated at the point of discharge (i.e. tailpipe tip). Obviously, if the tip terminates at your door or immediately under the passenger compartment, the sound level will be much greater at the exhaust discharge point than if the tip exits the rear of the vehicle, but this is common sense.

Assuming that there are no exhaust system leaks and isolators are correctly installed at all mounting points, what is not acceptable by industry standards, is when an exhaust system has been installed correctly, exiting well past the passenger compartment to have substantial exhaust sound transfer into the passenger compartment at a level which does not allow a person to talk without raising their voice to well above ambient noise levels. Whether you love to hear your engine roar (which I do), stereo blast or have a conversation, this interferes with your ability to enjoy what you like.

Now for the Causes

The first problem is most muffler shop staff today have little to no knowledge of exhaust systems, the “tricks” to installing a system that will “please” the customer, and simply verbally repeat the marketing materials provided to them by the system manufacturer. As previously noted by several others, there are 3 basic muffler designs, Absorption, Diffusion, and Chamber (Resonator), no matter which one suits your ear best, the criteria for promoting unnecessary in-cabin noise is the same.

Impactors:

Exhaust system material thickness should be no less than 16 gauge- double-walled pipe was commonly available through the 1970’s until manufacturers began seeking ways to reduce costs. Many of the “Muffler Chains” who marketed lifetime warranties always used double-walled pipe before “stainless steel” became the “in-crowd”. If a shop had it available, I would choose double-walled aluminized coated steel or 14 gauge stainless steel (depending on environmental conditions or personal tastes) - it is very quiet, solid and in terms of costs, pipe is pretty cheap, depending on length, 16 gauge aluminum coated runs about $11 to $20 wholesale (depending on diameter), stainless about double for the same gauge.

The muffler should be located as close to the axle (far away from the passenger compartment) as possible, allowing at least 3” of straight run pipe before a bend occurring (if installed to the forward position of the axle), with the overall length as long as possible. In the oem location, 24" will fit fine, located at the head pipe, 30" will fit fine as well and eliminate almost any possibility of drone in this particular location due to the size, length and insulation qualities (and yes, Allied does make units this long).

With regards to the 5.4/4.6 engines, The head-pipe (the pipe installed in between the exhaust manifold and the muffler) should be no greater in inside diameter the 2 7/8”, at 3” it now becomes a contributor.

Duel Tailpipes should be limited to no greater than 2.25” inside diameter, single tailpipes 3” maximum inside diameter- tips which are larger can certainly be installed but should be limited to 12” in length and have a discharge point past any material that may “catch” a sound wave or exhaust. When you exceed these diameters, it now becomes a contributor.

Tailpipe length in general should be as short as possible, minimal bends, etc, terminating past the axle, 1.5" past the body or bumper. Lengths greater than 4 feet promote “drone” (i.e. harmonics), typically about 3 ½ feet past the muffler.

Pipe diameter reduction should occur before the muffler. While many muffler installers like to use mufflers which reduce pipe diameter or split the exhaust at the point of discharge at the muffler, or install reducers to connect the tailpipes after the muffler induces “noise”.

Ultimately, it is the quality of the material and the installer which 90% of the time leads to a successful installation. I would like to also emphasize that it is not necessary to spend a fortune on a muffler ($100+) or system to have an excellent sounding, performing and long lasting result.

 

It's the Magnaflow cat back kit. It exits behind the rear passenger tire. The muffler that came with the kit is a 5x11 oval with a 22" core length. I think it is the biggest they make. Would it be quiter with one of the Magnaflow XL mufflers, which look to be a little more like a turbo muffler? Otherwise I was thinking a Dynamax super turbo.

 

I called Magnaflow. My muffler is the quietest they make. They suggested adding one of their 4" or 5" round mufflers in line as a resonator. Thoughts on that?

 

Would a larger diameter round muffler be quieter than a smaller diameter?

 

Larger Oval body... round is going to be louder

 

I'm looking at doing one in addition to the oval that is on there, as Magnaflow suggested. I'm just wondering/assuming that the larger diameter is quieter since it holds more fiberglass. True?

 

O I see what you mean, the internal case volume is what decides how much louder it would be. I would think an oval would quiet it done more

 

Same issue with a few of my trucks in the past. The best fix would be to install a resonator/glass pack/short round muffler just aft of the mid/y-pipe and forward of the muffler. It will tone it down enough to tolerate the drone. My Maggies always droned at 70 mph.

Best of luck,
James

 

x2.....

 

The super turbo is a quiet muffler especially at idle, but its just right for me. It gets loud when you open it up a little. I have one on my truck which is quite a bit older than your vehicle. I would run this muffler again, but only if it was available in stainless steel. I suggest you go with an additional magnaflow like you mentioned you were going to do, or try something different and replace your current Maggie for a dynomax ultraflo if there is a sized articulate size magnaflow doesn't have.

 

*Particular not articulate