I recently installed a Magnaflow Cat-Back system on the 5.0 F150. Part Number 15461. The in cab drone is too load for me especially at cruising speed.

What are my options?

Option One: Replace resistor that was in front of stock muffler, which would require cutting off the mounting rod from the magnaflow lead in piece and welding to the resistor to hold the weight, and the maganaflow muffler does not have hangers like the stock one does.

Option two: Replace the 18" muffler that came with the kit with a new magnaflow muffler part number 12388 which is a 24" muffler $120.00 purchase. This would require cutting some of the lead in pipe to accommodate the extra length in muffler.

Please help, what woudl you all do.

 

Add a muffler or glasspack in front of it.......

 

Do you mean resonator? I would go with the 24 inch muffler.

 

I'm surprised your getting drone at all. Did you butcher the system or something?

 

I was surprised myself, as quiet as the 18" are. maybe the 5.0 is naturally louder. I know my stocker makes a little noise when you get on it.

 

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.

If all of this is done correctly and there is still drone.....it is harmonic based.....then install the longest resonator you can in front of the muffler.

 

x2 24".

 

The resonator will not do much, replace with the larger body muffler.

 

I had a similar system on my truck and the drone too was horrendous. Only lasted about a week on there before I swapped it out for the Corsa.

 

I have the exact same kit on my 2011 and it drones REALLY bad. I put a glasspack in front of it, and it helped slightly, but I'm not totally happy with that fix. Kinda made it sound really quiet at times, and still drone at others. I think I'll eventually swap to the 24 instead.

 

Depends.....

 

I have a suspicion that the rules have changed with the 5.0. I suspect that what could be said for the 5.4 may not fully apply due to the different exhaust characteristics of the engine. My 5.0 revs much faster than my 5.4 and produces a totally different sound. I think we may go through an experimental learning curve as to what works and doesn't.

 

It would be nice to know weather or not the resonator is chambered or a flow through design.....

 

Let alone the 09+ 5.4's. Since 2009 The F150s have become much much louder. What people considered tame on a F150 is no longer applicable. A 22-24" maggie on a 2009+ is most likely comparable to an 18" on the 97-2008's

 

If you are referring to the factory resonator, it is a flow through. I remember looking at it when it was removed from mine.