Still didn't do the paint technique, but willing to spend another $100+ on mufflers- ok, I'm gone, walking away shaking my head.

 

I was aware of this old school crayon/paint trick before I had the first X pipe put in but things aren't always ideal. The pipes have been painted for over 2 years now with a spray enamel paint, nothing special. The only area the paint has naturally burned off is just behind the cats and forward of that. The piping would have to seriously get redone to fit a crossover in that area. There's probably very few members here on this site that actually used the paint method in placing the crossover. I'm not saying it doesn't work, it's just doesn't always work out so perfectly. I do appreciate your advice though.

In this pic, notice the driver's side pipe on the left is just peaking up and over the large torsion bar crossmember after wrapping around the transfer case. The crossover pipe is placed not very far back from there; there's not a whole lot you can do there.

 

I'm sorry about your situation.

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. It is enhanced also when pulsations are created internally that are in direct conflict with each other. Correctly deployed, theses same pulses will cancel out all drone as well.


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.

 

^ Do you copy and paste that every week?

 

Thanks beechkid. Those are the reasons why I have a flowmaster and it doesn't drone. Surprisingly quiet in fact. On the highway cruising it's like a siso Maggie. Till I hammer it. Then the high flows and shorties sound better but I love talking and hearing my radio. I'm getting duals soon, the short maggies and x. But I don't wanna miss the quiet so I'm gonna take what you said into consideration. My uncle has I pipe bender and I a welder so I can't wait to see my creation...

Since it's so quiet I may change the exhaust exit from straight out to 45ed.

Flowmaster has been there 6 years and is hollowed out. Time for upgrade. Surprisingly sounds good. I think it's funny when people come up to me and ask about it. And when I leave the house at 5am I feel bad...